A REPORT ON THE CHEMICAL QUALITY OF NEW ZEALAND’S ... · A Report on the Chemical Quality of New Zealand’s June 2001 Community Drinking Water Supplies 3.7.3 Conclusions, implications

A REPORT ON THE CHEMICAL QUALITY OF NEW ZEALAND’S COMMUNITY

DRINKING WATER SUPPLIES

Prepared as part of a Ministry of Health Contract for scientific services

By

Helen Davies Chris Nokes

Jacqui Ritchie

June 2001

Client Report FW0120

A REPORT ON THE CHEMICAL QUALITY OF NEW ZEALAND’S COMMUNITY

DRINKING WATER SUPPLIES

Alistair Sheat Water Science Programme Manager and Peer Reviewer

Helen Davies

Chris Nokes Jacqui Ritchie

A Report on the Chemical Quality of New Zealand’s June 2001 Community Drinking Water Supplies

DISCLAIMER This report or document ("the Report") is given by the Institute of Environmental Science and Research Limited ("ESR") solely for the benefit of the Ministry of Health, Public Health Service Providers and other Third Party Beneficiaries as defined in the Contract between ESR and the Ministry of Health, and is strictly subject to the conditions laid out in that Contract. Neither ESR nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for use of the Report or its contents by any other person or organization.


CONTENTS EXECUTIVE SUMMARY ........................................................................................................ i

RECOMMENDATIONS .......................................................................................................... vi

ABBREVIATIONS AND DEFINITIONS ............................................................................... ix

CHAPTER 1: INTRODUCTION .............................................................................................. 1

CHAPTER 2: METHODOLOGY ............................................................................................. 3 2.1 Introduction .................................................................................................................. 3 2.2 District Health Board areas ........................................................................................... 4 2.3 Surveillance programmes ............................................................................................. 4 2.4 The P2 Programme ....................................................................................................... 6 2.5 Sample analysis ............................................................................................................ 7 2.6 Extrapolation of results to multiple zones fed by a single treatment plant ................... 7 2.7 Detection limits and detections..................................................................................... 8 2.8 Statistical analysis of the data presented in this report ................................................. 9 2.9 Minimum, Median and Maximum concentrations ....................................................... 9 2.10 The relationship between determinands identified >50% MAV and source type ........ 9 2.11 Type of supply ............................................................................................................ 10 2.12 Use of the data in this report for small (unassessed) drinking-water supplies ........... 10

CHAPTER 3: SYNTHESIS OF KEY FINDINGS, AND PUBLIC HEALTH STRATEGIES.......................................................................................................................... 12

3.1 Introduction ................................................................................................................ 12 3.2 Chemical determinands of high public health significance ........................................ 12 3.3 Corrosion-derived metals ........................................................................................... 13

3.3.1 Introduction .......................................................................................................... 13 3.3.2 Population affected .............................................................................................. 13 3.3.3 Conclusions, implications and possible strategies for reducing exposures to corrosion-derived metals in New Zealand drinking waters .............................................. 15

3.4 Arsenic ........................................................................................................................ 19 3.4.1 Introduction .......................................................................................................... 19 3.4.2 Populations affected ............................................................................................. 19 3.4.3 Conclusions, implications and possible strategies for reducing exposures to arsenic in New Zealand drinking waters ........................................................................... 20

3.5 Disinfection by-products ............................................................................................ 22 3.5.1 Introduction .......................................................................................................... 22 3.5.2 Conclusions, implications and possible strategies for reducing exposures to disinfection by-products in New Zealand drinking waters ............................................... 24

3.6 Nitrate ......................................................................................................................... 29 3.6.1 Introduction .......................................................................................................... 29 3.6.2 Population affected .............................................................................................. 29 3.6.3 Conclusions, implications and possible strategies for reducing exposures to nitrate in New Zealand drinking waters ............................................................................ 30

3.7 Manganese .................................................................................................................. 32 3.7.1 Introduction .......................................................................................................... 32 3.7.2 Population affected .............................................................................................. 32


3.7.3 Conclusions, implications and possible strategies for reducing exposures to manganese in New Zealand drinking waters..................................................................... 33

3.8 Chemical determinands that have been assessed and identified above 50% MAV in distribution zones that serve a low population ..................................................................... 34 3.9 Chemical determinands that have been assessed and not identified above 50% MAV in any distribution zones ....................................................................................................... 34 3.10 Chemical determinands that have not been assessed .................................................. 35

CHAPTER 4: INORGANICS.................................................................................................. 36 4.1 Introduction ................................................................................................................ 36 4.2 Origins of the analytical data ...................................................................................... 36

4.2.1 Surveillance Programmes .................................................................................... 36 4.2.2 P2 Programme Baseline sampling ....................................................................... 37 4.2.3 P2 Programme M1 and M2 rounds of sampling .................................................. 38 4.2.4 Fluoride ................................................................................................................ 38

4.3 Summary of results ..................................................................................................... 38 4.4 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) .................................................................................................................................. 40 4.5 Detections to 50% MAV ............................................................................................ 41 4.6 Geographical distribution ........................................................................................... 42 4.7 Source types ................................................................................................................ 42 4.8 Gaps in the information .............................................................................................. 42 4.9 Antimony .................................................................................................................... 43 4.10 Aggressiveness ........................................................................................................... 45 4.11 Arsenic ........................................................................................................................ 46 4.12 Barium ........................................................................................................................ 51 4.13 Beryllium .................................................................................................................... 53 4.14 Boron .......................................................................................................................... 54 4.15 Cadmium .................................................................................................................... 56 4.16 Chlorine (free) ............................................................................................................ 58 4.17 Chromium ................................................................................................................... 59 4.18 Copper ........................................................................................................................ 61 4.19 Cyanide (total) ............................................................................................................ 63 4.20 Fluoride 2a .................................................................................................................. 64 4.21 Fluoride 2b .................................................................................................................. 65 4.22 Lead ............................................................................................................................ 67 4.23 Lithium ....................................................................................................................... 69 4.24 Manganese .................................................................................................................. 70 4.25 Mercury (total) ............................................................................................................ 73 4.26 Molybdenum ............................................................................................................... 74 4.27 Nickel.......................................................................................................................... 76 4.28 Nitrate ......................................................................................................................... 78 4.29 Nitrite .......................................................................................................................... 81 4.30 Selenium ..................................................................................................................... 82 4.31 Silver ........................................................................................................................... 84 4.32 Tin ............................................................................................................................... 85 4.33 Uranium ...................................................................................................................... 87

CHAPTER 5: DISINFECTION BY-PRODUCTS (DBPs) ..................................................... 88 5.1 Introduction ................................................................................................................ 88 5.2 DBP families/groups................................................................................................... 89


5.3 Origins of the analytical data ...................................................................................... 90 5.3.3 P2 Programme: Baseline sampling ...................................................................... 90 5.3.4 P2 Programme: M1 and M2 sampling ................................................................. 90

5.4 Summary of results ..................................................................................................... 91 5.5 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) .................................................................................................................................. 91 5.6 Detections to 50% MAV ............................................................................................ 92 5.7 Geographical distribution ........................................................................................... 94 5.8 Source types ................................................................................................................ 95 5.9 Unassessed zones ........................................................................................................ 95 5.10 Gaps in the information .............................................................................................. 95

5.10.1 Disinfection using ozonation ............................................................................... 95 5.10.2 Limitations of laboratory measurements ............................................................. 96 5.10.3 Disinfection using chlorine dioxide ..................................................................... 96 5.10.4 Inadequate limits of detection .............................................................................. 96 5.10.5 Absence of MAVs................................................................................................ 96

5.11 Bromate ...................................................................................................................... 97 5.12 Bromodichloromethane THM .................................................................................... 98 5.13 Bromoform THM ..................................................................................................... 100 5.14 Chlorate .................................................................................................................... 102 5.15 Chlorite ..................................................................................................................... 105 5.16 Chloroform THM ..................................................................................................... 106 5.17 Cyanogen chloride (as CN) ...................................................................................... 108 5.18 Dibromoacetonitrile .................................................................................................. 109 5.19 Dibromochloromethane THM .................................................................................. 110 5.20 Dichloroacetic acid HAA ......................................................................................... 112 5.21 Dichloroacetonitrile .................................................................................................. 114 5.22 Dichloromethane ...................................................................................................... 115 5.23 Formaldehyde ........................................................................................................... 116 5.24 Monochloramine ....................................................................................................... 117 5.25 Trichloroacetaldehyde/chloral hydrate ..................................................................... 118 5.26 Trichloroacetic acid HAA ........................................................................................ 119 5.27 Trichloroacetonitrile ................................................................................................. 121 5.28 Trihalomethanes (THMs) ......................................................................................... 122 5.29 Haloacetic acids (HAAs) .......................................................................................... 124 5.30 Bromochloroacetic acid ............................................................................................ 126 5.31 Dibromoacetic acid ................................................................................................... 127 5.32 Monochloroacetic acid ............................................................................................. 128 5.33 Bromochloroacetonitrile ........................................................................................... 129 5.34 Bromochloromethane ............................................................................................... 130 5.35 Dibromomethane ...................................................................................................... 131 5.36 1,1-Dichloropropan-2-one ........................................................................................ 132 5.37 1,1,1-Trichloropropan-2-one .................................................................................... 133

CHAPTER 6: PESTICIDES .................................................................................................. 134 6.1 Introduction .............................................................................................................. 134 6.2 Origins of the analytical data .................................................................................... 136

6.2.1 P2 Programme: Baseline sampling .................................................................... 136 6.2.2 P2 Programme: M1 and M2 sampling ............................................................... 136

6.3 Summary of results ................................................................................................... 136


6.4 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) ................................................................................................................................ 138 6.5 Detections to 50% MAV .......................................................................................... 138 6.6 Geographical distribution ......................................................................................... 138 6.7 Source types .............................................................................................................. 139 6.8 Unassessed zones ...................................................................................................... 139 6.9 Alachlor .................................................................................................................... 140 6.10 Aldicarb .................................................................................................................... 141 6.11 Aldrin + Dieldrin ...................................................................................................... 142 6.12 Atrazine .................................................................................................................... 143 6.13 Azinphos methyl ....................................................................................................... 144 6.14 Bentazone ................................................................................................................. 145 6.15 Bromacil ................................................................................................................... 146 6.16 Carbofuran ................................................................................................................ 147 6.17 Chlordane.................................................................................................................. 148 6.18 Chlorpyriphos ........................................................................................................... 149 6.19 Chlortoluron.............................................................................................................. 150 6.20 Cyanazine ................................................................................................................. 151 6.21 2,4-D ......................................................................................................................... 152 6.22 2,4-DB ...................................................................................................................... 153 6.23 DDT + isomers ......................................................................................................... 154 6.24 Diazinon.................................................................................................................... 155 6.25 1,2-Dibromo-3-chloropropane .................................................................................. 156 6.26 1,2-Dichloropropane ................................................................................................. 157 6.27 1,3-Dichloropropene ................................................................................................. 158 6.28 Dichlorprop ............................................................................................................... 159 6.29 Diquat ....................................................................................................................... 160 6.30 Diuron ....................................................................................................................... 161 6.31 Fenoprop ................................................................................................................... 162 6.32 Heptachlor and heptachlor epoxide .......................................................................... 163 6.33 Hexachlorobenzene .................................................................................................. 164 6.34 Hexazinone ............................................................................................................... 165 6.35 Isoproturon................................................................................................................ 166 6.36 Lindane ..................................................................................................................... 167 6.37 MCPA ....................................................................................................................... 168 6.38 Mecoprop .................................................................................................................. 169 6.39 Metalaxyl .................................................................................................................. 170 6.40 Methoxychlor............................................................................................................ 171 6.41 Metolachlor ............................................................................................................... 172 6.42 Metribuzin ................................................................................................................ 173 6.43 Molinate .................................................................................................................... 174 6.44 Oryzalin .................................................................................................................... 175 6.45 Oxadiazon ................................................................................................................. 176 6.46 Pendimethalin ........................................................................................................... 177 6.47 Pentachlorophenol .................................................................................................... 178 6.48 Permethrin ................................................................................................................ 179 6.49 Picloram .................................................................................................................... 180 6.50 Pirimiphos methyl..................................................................................................... 181 6.51 Pirimisulfuron methyl ............................................................................................... 182 6.52 Procymidone ............................................................................................................. 183


6.53 Propanil ..................................................................................................................... 184 6.54 Propazine .................................................................................................................. 185 6.55 Pyridate ..................................................................................................................... 186 6.56 Simazine ................................................................................................................... 187 6.57 2,4,5-T ...................................................................................................................... 188 6.58 Terbuthylazine .......................................................................................................... 189 6.59 Thiabendazole ........................................................................................................... 190 6.60 Triclopyr ................................................................................................................... 191 6.61 Trifluralin.................................................................................................................. 192 6.62 1080 .......................................................................................................................... 193

CHAPTER 7: ALGAL TOXINS ........................................................................................... 194 7.1 Introduction .............................................................................................................. 194 7.2 Future assessment of algal toxins ............................................................................. 194

CHAPTER 8: OTHER ORGANICS ..................................................................................... 195 8.1 Introduction .............................................................................................................. 195 8.2 Origins of the analytical data .................................................................................... 195

8.2.1 P2 Programme: Baseline sampling .................................................................... 195 8.2.2 P2 Programme: M1 and M2 sampling ............................................................... 196

8.3 Summary of results ................................................................................................... 196 8.4 Aromatic hydrocarbons ............................................................................................ 197 8.5 Chlorinated hydrocarbons......................................................................................... 198 8.6 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) ................................................................................................................................ 198 8.7 Detections to 50% MAV .......................................................................................... 198 8.8 Geographical distribution ......................................................................................... 199 8.9 Source types .............................................................................................................. 199 8.10 Unassessed zones ...................................................................................................... 199 8.11 Information gaps ....................................................................................................... 199 8.12 Acrylamide ............................................................................................................... 201 8.13 Benzene .................................................................................................................... 202 8.14 Benzo(a)pyrene ......................................................................................................... 203 8.15 Carbon tetrachloride ................................................................................................. 204 8.16 Di(2-ethylhexyl)adipate ............................................................................................ 205 8.17 Di(2-ethylhexyl) phthalate ........................................................................................ 206 8.18 1,2-Dichlorobenzene ................................................................................................. 207 8.19 1,4-Dichlorobenzene ................................................................................................. 208 8.20 1,2-Dichloroethane ................................................................................................... 209 8.21 1,1-Dichloroethene ................................................................................................... 210 8.22 1,2-Dichloroethene ................................................................................................... 211 8.23 Dichloromethane ...................................................................................................... 212 8.24 1,2-Dichloropropane ................................................................................................. 213 8.25 EDTA........................................................................................................................ 214 8.26 Epichlorohydrin ........................................................................................................ 215 8.27 Ethylbenzene ............................................................................................................ 216 8.28 Fluoranthene ............................................................................................................. 217 8.29 Hexachlorobutadiene ................................................................................................ 218 8.30 Monochlorobenzene ................................................................................................. 219 8.31 Nitrilotriacetic acid ................................................................................................... 220 8.32 PAHs ......................................................................................................................... 221


8.33 Styrene ...................................................................................................................... 222 8.34 Tetrachloroethene ..................................................................................................... 223 8.35 Toluene ..................................................................................................................... 224 8.36 Tributyltin oxide ....................................................................................................... 225 8.37 Trichlorobenzenes (total) .......................................................................................... 226 8.38 1,1,1-Trichloroethane ............................................................................................... 227 8.39 Trichloroethene ......................................................................................................... 228 8.40 2,4,6-Trichlorophenol ............................................................................................... 229 8.41 Vinyl chloride ........................................................................................................... 230 8.42 Xylenes ..................................................................................................................... 231

REFERENCES ...................................................................................................................... 232

APPENDIX 1: INORGANIC DETERMINANDS OF HEALTH SIGNIFICANCE ............ 234

APPENDIX 2: DISINFECTION BY-PRODUCTS (DBPs) OF HEALTH SIGNIFICANCE .................................................................................................................... 264

APPENDIX 3: PESTICIDES OF HEALTH SIGNIFICANCE............................................. 294

APPENDIX 4: OTHER ORGANICS OF HEALTH SIGNIFICANCE ................................ 300


LIST OF TABLES Table 3.1 Drinking-water distribution zones with corrosion metals identified at greater than

50% MAV – by distribution zone size .................................................................... 14 Table 3.2 Drinking-water distribution zones with arsenic identified at greater than 50% MAV

– by distribution zone size ...................................................................................... 19 Table 3.3 Drinking-water distribution zones with disinfection by-products identified at

greater than 50% MAV – by distribution zone size ................................................ 23 Table 3.4 Drinking-water distribution zones with nitrate identified at greater than 50% MAV

– by distribution zone size ...................................................................................... 29 Table 3.5 Drinking-water distribution zones with manganese identified at greater than 50%

MAV – by distribution zone size ............................................................................ 32 Table 3.6 Chemicals identified at greater than 50% MAV in distribution zones that serve low

total populations ...................................................................................................... 34 Table 3.7 Chemicals that have never been detected at greater than 50% MAV in distribution

zones ....................................................................................................................... 34 Table 3.8 Pesticides and ‘other organics’ detections in distribution zones ............................. 35 Table 3.9 Chemicals that have not been assessed in community drinking-water supplies ..... 35 Table 4.1 Inorganic determinands of health significance listed in the DWSNZ:1984 (BoH

1984) ....................................................................................................................... 37 Table 4.2 Analytical suite of the ‘Baseline’ sampling round of the P2 Programme ............... 37 Table 4.3 Summary table for inorganic determinands ............................................................ 39 Table 4.4 Inorganic determinands detected at greater than 50% MAV or transgressing their

MAV ....................................................................................................................... 40 Table 4.5 Drinking-water distribution zones located outside the Central Plateau/Waikato

River area in which arsenic has been identified at greater than 50% MAV ........... 49 Table 4.6 The relationship between various source types and the identification of arsenic in

drinking-water distribution zones at greater than 50% MAV ................................. 49 Table 5.1 Disinfection by-product chemical families ............................................................. 89 Table 5.2 Summary table for disinfection by-products ........................................................... 91 Table 5.3 Disinfection by-products detected at greater than 50% MAV or transgressing their

MAV ....................................................................................................................... 92 Table 5.4 Disinfection by-products that have not been detected in any distribution zones .... 92 Table 5.5 Range & medians for all disinfection by-products detections, plus analytical limits

of detection.............................................................................................................. 93 Table 6.1 Use and chemical families for the pesticides included in the DWSNZ:2000 ........ 134 Table 6.2 Summary table for pesticides ................................................................................ 137 Table 6.3 Pesticides detected in community drinking-water supplies .................................. 138 Table 7.1 Algal toxins for which MAVs have been allocated .............................................. 194


LIST OF FIGURES Figure 2.1: Schematic diagram of a drinking-water supply system ......................................... 3 Figure 2.3: The stages involved in the assessment of a drinking water supply ........................ 6 Figure 4.1: Populations served by distribution zones in which inorganic determinands have

been identified in their drinking-water supply at greater than 50% Maximum Acceptable Value .................................................................................................... 41

Figure 4.2 Arsenic detections have been found to have a geographic relationshipDetection of arsenic in distribution zones, presented by region .................................................. 47

Figure 5.1 Populations served by distribution zones in which disinfection by-products have been identified at greater than 50% Maximum Acceptable Value ......................... 94

A Report on the Chemical Quality of New Zealand’s i June 2001 Community Drinking Water Supplies

EXECUTIVE SUMMARY Background A number of factors affect the health of a community. One of these is the quality of the community’s drinking-water supply, which, if poor, can have wide-spread health and economic consequences. Reducing the exposure of the public to microbiological and chemical determinands of health significance contained in their drinking water is therefore an important step in protecting the health of a community. For informed decisions to be made about the allocation of resources for minimizing exposure to disease-causing agents in a water supply, information about the levels of exposure to these agents, their sources, mitigation options, and the maximum acceptable levels of exposure, is needed. Chemical determinands that are present in specific distribution zones at potentially health-significant concentrations (greater than 50% MAV) are classified as ‘Priority 2’ determinands and generally must be monitored for compliance with the Drinking-Water Standards for New Zealand: 2000. Concentrations of chemicals that transgress their MAVs are health significant, and should be addressed without delay. This report addresses the presence of chemicals in New Zealand’s community drinking-water supplies. It has the objective of presenting the national and regional distribution of concentrations for each determinand, and discussing the health significance of the data. It does not address compliance with the Standards as the data to do this are not available. There are a total of 133 chemical determinands listed with MAVs in Tables 14.2 to 14.7 of the Standards. Of these, 98 have been assessed, and are included in this report. The determinands consist of 20 inorganics, 17 disinfection by-products, 36 pesticides, and 25 other organics. Of the 2061 distribution zones listed in the Register of Community Drinking-Water Supplies in New Zealand, 859 distribution zones, serving a population of approximately three million people, have been fully assessed for chemical determinands through the Priority 2 Identification Programme, and results are reported here. In all cases the data presented in this report relate to consumer exposure rather than source water quality. As such, results are expressed in terms of their occurrence in drinking-water distribution zones (at the consumer’s tap). Key findings The determinand that has been identified at greater than 50% MAV for the largest population is fluoride (approximately 1.9 million). This is a result of its intentional addition at treatment plants, for oral health reasons. The Ministry of Health has listed improvement of oral health as one of its 13 population health objectives in the New Zealand Health Strategy (MoH, 2000c), and the intentional addition of fluoride to drinking-water is consistent with this objective. The chemical determinands that have been found to be of greatest public health significance – based on population exposed - in New Zealand’s community drinking-waters are the corrosion-derived metals, arsenic, disinfection by-products, and nitrate.

A Report on the Chemical Quality of New Zealand’s ii June 2001 Community Drinking Water Supplies

Corrosion-derived metals Five corrosion-derived metals, antimony, cadmium, copper, lead and nickel have collectively been identified at greater than 50% MAV in distribution zones serving approximately 860,000 people. Of these metals, lead is of greatest concern, having been identified in 323 zones that serve a total population of approximately 612,000 people. Lead, nickel, cadmium and copper have all been identified at concentrations transgressing the MAV in distribution zones that serve significant populations. Antimony, although identified at greater than 50% MAV in distribution zones that serve a high population, has not been identified at concentrations transgressing the MAV in many zones. The frequent identification of these metals in drinking-water is of high public health significance based on the populations exposed. The Ministry of Health has investigated the widespread occurrence of corrosion-derived metals in New Zealand’s community drinking-water supplies. It has found that the concentration of all corrosion derived metals, with the exception of copper, can usually be effectively reduced by flushing of the tap (Nokes 1999). A longer term option is improvement of the quality of metal plumbing fittings. For copper identified at greater than 50% MAV, the strategy of flushing has been shown to be less effective. It is considered that copper pipework and fittings should not be recommended for distribution of drinking-water in situations where the water is known to be markedly aggressive. Treatment to reduce the aggressiveness of water may be an option where copper is already in place, and has been identified in drinking-water at health significant concentrations. Treatment to reduce aggressiveness is an option that can also be used to manage elevated concentrations of other corrosion-derived metals. Schools have been found to be more likely to have corrosion-derived metals identified at greater than 50% MAV than other types of supply. This situation was especially true for copper. Tap flushing, where the corrosion-derived metal is not copper, should be encouraged, as should maintenance checks of roof catchments where rain water is the source. Treatment to reduce the aggressiveness of the water, or replacement of plumbing material are possible options where the metal is copper. Arsenic Arsenic has been identified at concentrations exceeding greater than 50% MAV in 70 distribution zones that serve a total population of approximately 285,000. It can therefore be considered to be of high public health significance. The distribution of arsenic has a geographic relationship, considered to be related to its geothermal origin, and 80% of these 285,000 people are located in the Central Plateau and Waikato areas. All except one of the 28 distribution zones in which arsenic was identified at concentrations transgressing the MAV have been in these areas, and these zones serve a total population is approximately 21,000. The higher risk factor used calculation of the MAV – for an excess lifetime skin cancer risk of 6 x 10-4 (1 in every 1,700 people), rather than the risk of 1 x 10-5 (1 in every 100,000 people) for other carcinogens - is notable. Because the majority (87%) of the population receiving water in which arsenic has been identified at greater than 50% MAV are served by only ten zones, improved management of the treatment processes associated with these few zones would significantly reduce the size of

A Report on the Chemical Quality of New Zealand’s iii June 2001 Community Drinking Water Supplies

the population affected. There are three factors of relevance to strategies to reduce arsenic exposure: • the ease with which water from Lake Taupo and the Waikato River can be treated; • the ease with which groundwater can be treated; • the oxidation state of the arsenic in the source water (which has been found to be

important in the effectiveness of treatment (Gregor, 2001)). Populations in the Pacific Health Rotorua and Whakatane area and those populations receiving water from Lake Taupo or the Waikato River are particularly affected by arsenic in their drinking-water. Disinfection by-products Disinfection by-products have been identified in distribution zones that serve a wide range of population sizes and affect a large total population. They can therefore be considered to be of high public health significance. Disinfection by-products in which results that exceed 50% MAV affect a large number of zones are: chloral hydrate, chlorate, dichloroacetic acid, trichloroacetic acid, haloacetic acids and trihalomethanes. Of these, chloral hydrate has been identified most frequently (75 zones), and chlorate, has been identified at concentrations greater than 50% MAV in zones serving the highest total population (424,000 people) largely due to the contribution of one major treatment plant. However, the population receiving drinking-water from a distribution zone in which chlorate transgresses the MAV is relatively low (1,500 people). Factors that are likely to lead to elevated chlorate concentrations in finished water are well described in the literature, and water suppliers should be made aware of these. Steps taken to reduce any of the haloacetic acids or trihalomethanes will reduce disinfection by-product formation as a whole, because much of the pathway by which they are formed is common. There is no apparent link between the size of the distribution zone and the identification of disinfection by-products at greater than 50% MAV. However, for some disinfection by-products a few larger zones account for more than half of the affected population. Addressing the disinfection by-product issues for these zones would significantly reduce the population affected. The disinfection by-product that has been identified at concentrations that transgress the MAV in distribution zones that serve the highest population is the haloacetic acid family (HAAs) – approximately 56,000 people. A large percentage of this population is contained in two large distribution zones. Disinfection by-products are not a significant issue for schools because few schools chemically disinfect their water on a continuous basis. Disinfection by-product formation is most marked in south east Otago, Wellington and Manawatu, Taranaki, Central North Island and through the Waikato up to Auckland and Western Bay of Plenty. Disinfection by-product formation is usually greater when surface

A Report on the Chemical Quality of New Zealand’s iv June 2001 Community Drinking Water Supplies

waters are used rather than groundwaters, and also tends to be greater when the surface water is a river or stream rather than a lake or reservoir. Some of the disinfection by-products have been identified at concentrations below, but close to, 50% MAV, and this suggests that they could easily rise above 50% MAV. Addressing the factors that are responsible for the appearance of these disinfection by-products is recommended. Disinfection by-products associated with the use of ozonation and chlorine dioxide as disinfectants are not considered to be a significant public health issue, because of the lack of distribution zones receiving water disinfected by these methods. Nitrate Nitrate has been identified at concentrations exceeding 50% MAV in 50 distribution zones that serve a total population of approximately 100,000. Only 1,017 people are supplied by a distribution zone in which nitrate had been identified at a concentration transgressing the MAV. The majority (90%) of the population receiving water in which nitrate has been identified at greater than 50% MAV are served by two large zones, and one major zone. If the nitrate concentrations were reduced in these three zones, the population affected would be significantly reduced. 86% of the distribution zones in which nitrate has been identified at greater than 50% MAV are served by water from a groundwater source. This has two implications: Firstly, use of groundwater as a source water to supply zones that have not been assessed carries an increased possibility of elevated nitrate concentrations than use of other types of source water. Secondly, the apparent vulnerability of groundwater to nitrate contamination, is of relevance to those with responsibility for managing its quality. Nitrate is a greater concern to schools supplies than other supply types, with approximately one in six school supplies having nitrate identified at greater than 50% MAV. The Ministry of Education should be informed of this result so that it can take appropriate action. In general, small supplies are more likely to have nitrate identified at greater than 50% MAV than large supplies, and this, along with the complexity associated with reducing the inputs from land-use practises, makes management to reduce exposure more difficult. Other results Many inorganic determinands (other than arsenic and nitrate) were frequently detected in distribution zones at concentrations below 50% MAV. This is considered to result from the relatively low limits of detection combined with the naturally ubiquitous presence of many in the environment. They are generally not a national public health issue, but may occasionally be locally important. Of the pesticides that have been assessed (36 of the 54 listed in the Standards), five have been detected. These are: dieldrin (3 zones), simazine (1 zone), 2,4,5-T (1 zone), terbuthylazine (2 zones) and triclopyr (2 zones). Only one of these – dieldrin – has been

A Report on the Chemical Quality of New Zealand’s v June 2001 Community Drinking Water Supplies

identified at concentrations greater than 50% MAV. Dieldrin has been identified in two zones that serve a total population of 360. Pesticides are generally of low public health significance in the drinking-water supplies that have been assessed. However, their identification in trace amounts is of note with respect to contamination of water resources by land-use activities. Of the remaining organic determinands that are neither disinfection by-products, nor pesticides, and are termed ‘other organics’ in this report, eleven were detected. These were: acrylamide (1 zone), benzene (4 zones), di(2-ethylhexyl)phthalate (7 zones), 1,4-dichlorobenzene (1 zone), ethylbenzene (2 zones), fluoranthene (1 zone), tetrachloroethene (7 zones), toluene (4 zones), 1,1,1-trichloroethane (1 zone), trichloroethene (1 zone) and xylenes (7 zones). Of these- only one – di(2-ethylhexyl)phthalate has been identified at greater than 50% MAV (in one zone serving a population of 121). Of these organic determinands, acrylamide is a contaminant introduced with treatment chemicals (polyelectrolytes), di(2-ethylhexyl)phthalate is a plasticiser likely to have been introduced by contact with plastic distribution pipework. The other nine determinands are contaminants that can be generally attributed to land-use activities. ‘Other organics’ are generally of low public health significance in the community drinking-water supplies that have been assessed. However, their identification in trace amounts is of note with respect to contamination by land-use activities. Thirty five of the 133 chemical determinands that have MAVs allocated in the Standards have not been assessed. These consist of three inorganics, two disinfection by-products, eighteen pesticides, all eight algal toxins and four ‘other organics’.

A Report on the Chemical Quality of New Zealand’s vi June 2001 Community Drinking Water Supplies

RECOMMENDATIONS The following recommendations are made on the basis of information gathered for the preparation of this report. They are not listed in any order of priority: Corrosion-derived metals 1. That the instruction to flush and discard at least 500mL of water from the tap before it is

used for food preparation or drinking, as described in the DWSNZ:2000, be publicised as a generally effective public health initiative. This will help to ensure that those water suppliers less familiar with the DWSNZ:2000 are aware of this simple remedial strategy.

2. That treatment methods effective in reducing the dissolution of metals from plumbing fittings by New Zealand’s drinking-water be determined.

3. That the use of copper as a plumbing material for drinking-water be discouraged in situations where the water is known to be markedly aggressive.

Arsenic 4. That the suppliers of the ten large distribution zones with arsenic identified at greater than

50% MAV be encouraged to investigate methods of reducing the arsenic concentration. 5. That a project be undertaken to collate information on treatment systems being developed

overseas, relating to arsenic in groundwater, and critically appraise these systems to establish their likely usefulness in the New Zealand context for reducing exposure.

6. That the arsenic concentrations, and oxidation states in New Zealand groundwaters be investigated as a starting point for establishing the most appropriate treatment.

7. That the factors affecting arsenic removal during conventional aluminium–based treatment described by Gregor, 2001 be followed up through investigation of options for improved treatment of water sourced from Lake Taupo and the Waikato River.

8. That Health Protection Officers in the Pacific Health Rotorua and Whakatane offices be informed of the high likelihood of arsenic being present in water supplies in their area, and that strategies to reduce their public health significance be determined for their use.

Disinfection by-products 9. That water suppliers be made aware of the factors likely to lead to elevated chlorate

concentrations in finished water. 10. That the high concentration of chlorate in water leaving Ardmore Treatment Plant

(TP00129) be investigated. 11. That a project be undertaken to disseminate information on what we already know about

disinfection by-product formation to small water suppliers. Nitrate 12. That the water suppliers and those with responsibility for land-use in the recharge zones

for Kitchener ((PUK002KI), Richmond (RIC002RI) and North-West Christchurch (CHR001NW) be encouraged to address the nitrate concentrations in these three zones.

13. That small water suppliers be assisted, by provision of information, to identify land-use practises that may cause nitrate loading of their water resources and to take action on the results. The information provided should be consistent with that contained in the model Public Health Risk Management Plan Guide (PHRMPG) for raw water.

A Report on the Chemical Quality of New Zealand’s vii June 2001 Community Drinking Water Supplies

14. That the Ministry of Education is informed of the nitrate results for schools in this report, and provided with information that can be disseminated to schools to help them address the issue.

15. That Health Protection Officers be supported to write submissions for resource consent applications that have the potential to increase nitrate loading to aquifers.

16. That reassessment of distribution zones for nitrate should be conducted when land-uses show that nitrate concentrations may have changed significantly.

17. That the relevant Ministries (Ministry of Agriculture and Forestry and Ministry for the Environment) responsible for land-use practises, and their management are informed of the nitrate results in this report.

General 18. That an annual survey and report of the monitoring of Priority 2 chemical determinands

by water suppliers for demonstration of compliance with the DWSNZ:2000 be initiated. This will provide information to determine whether the chemical quality of community drinking-water supplies is improving, and consequently a measure of how effective the Ministry of Health’s strategies are.

19. That chemical determinands currently unassessed be added to the Priority 2 Identification Programme assessment process where possible.

20. That the assessment of community drinking-water supplies serving populations less than 100 for Priority 2 determinands is considered, particularly for corrosion-derived metals, arsenic, disinfection by-products and nitrate.

21. That the variability of determinand concentrations with time be investigated when suitable time series of chemical compliance data become available. This will enable a more robust interpretation of the significance of sampling results on public exposure to chemicals in drinking-water.

A Report on the Chemical Quality of New Zealand’s viii June 2001 Community Drinking Water Supplies

QUICK START SUMMARY FOR INTERPRETATION OF THE DATA TABLES PRESENTED IN THIS REPORT

Sources of the data Data presented in this report have been gained from: • Ministry of Health/Department of Health surveillance programmes conducted prior to

1995; • Phase 1 of the Ministry of Health’s Priority 2 Identification Programme – the source of

the majority of data. Priority 2 Programme sampling Phase 1 of the Priority 2 Programme has been conducted through a series of Programme ‘Rounds’, each lasting approximately one year, e.g. the 96/97 Programme Round. Each Programme Round consists of three sets of sampling: 1. Baseline (B) sampling for analysis of a standard suite of inorganic analytes; 2. M1 sampling for a set of analytes targeted for each supply on the basis of information

collected through questionnaires; 3. M2 sampling – same as M1. Samples are generally taken following all processes at the treatment plant, to provide a representation of water quality reaching the consumer, rather than source water quality. The public health significance of chemicals identified at greater than 50% MAV This report has identified chemicals present in drinking-water distribution zones at greater than 50% MAV. This value is chosen to represent a concentration that is potentially health significant. The MAV is the Maximum Acceptable Value of a determinand in drinking-water, and it represents the concentration of a determinand below which the presence of the determinand does not result in any significant risk to the health of the consumer over a lifetime of consumption. For carcinogenic chemicals, the MAVs set in the Drinking-Water Standards for New Zealand:2000 generally represent a risk of one additional incidence of cancer per 100,000 people ingesting the water at the concentration of the MAV for 70 years.

A Report on the Chemical Quality of New Zealand’s ix June 2001 Community Drinking Water Supplies

ABBREVIATIONS AND DEFINITIONS The following definitions apply to abbreviations used in the text of this report. Abbreviations associated with particular tables of data are defined with the tables ATO Concentrations of the substance at below the health based guideline

may affect the appearance, taste and odour of the water. B Baseline round of sampling DBP Disinfection by-product Determinand A constituent or property of the water which is determined or estimated

in a sample, for example, total coliforms, chloride etc. DHB District Health Board Distribution zone The part of the drinking-water supply network within which all

consumers receive drinking-water of identical quality, from the same or similar sources, with the same treatment (full definition in DWSNZ:2000).

DWSNZ Drinking-Water Standards for New Zealand: 2000 ESR Environmental Science and Research Ltd HAA Haloacetic acid HPO Health protection officer IANZ International Accreditation New Zealand Large zone A drinking-water supply network serving a population of less than

50,000 but more than 10,000 persons. M1 and M2 First and second monitoring round Major zone A drinking-water supply network serving a population of greater than

50,000 persons MAV Maximum acceptable value Medium zone A drinking-water supply network serving a population of less than

10,000 but more than 5,001 persons Minor zone A drinking-water supply network serving a population of 501 – 5,000

persons MoH Ministry of Health nd Not detected PHRMP Public Health Risk Management Plan PHSP Public health service provider P2 Priority 2 (part of a classification system used in the DWSNZ:2000) PMAV Provisional Maximum Acceptable Value Small zone A drinking-water supply network serving a population of 101 – 500

persons THM Trihalomethane Transgression Concentration greater than the MAV

A Report on the Chemical Quality of New Zealand’s x June 2001 Community Drinking Water Supplies

WINZ Water Information New Zealand – a national community drinking-

water supply information system for New Zealand WHO World Health Organisation

A Report on the Chemical Quality of New Zealand’s 1 June 2001 Community Drinking Water Supplies

CHAPTER 1: INTRODUCTION This report presents data relating to the chemical quality of New Zealand’s community drinking water supplies. The objective of the report is to provide an overview of the national and regional distribution of concentrations for each determinand listed as health significant in the Drinking-Water Standards for New Zealand:2000, plus an overview of the significance of these data for New Zealand. This report is the first to detail what is known about the chemical quality of New Zealand’s community drinking-water supplies that has been produced since the Drinking-Water Standards for New Zealand, 1995 was introduced. It is anticipated that it will provide useful policy direction to those with responsibility for the management of drinking-water supplies and water resources. The last report of this type was produced in two volumes, the first in February 1991, and the second in March 1992 (Mattingley 1991, 1992). That report presented a data review for the period 1983 – 89 and used the Drinking-Water Standards for New Zealand: 1984 as a ‘yardstick’ for assessing public health significance. The Drinking-Water Standards for New Zealand 1995 introduced an extensive range of chemicals (determinands) of potential health significance. It also introduced a priority classification procedure for demonstrating compliance. To demonstrate compliance with the Standards, only those relatively few determinands that fall into the classes with highest potential risk, Priorities 1 and 2, are required to be monitored. Monitoring of determinands in the classes with lower potential risk, Priorities 3 and 4, is at the discretion of the supplier, unless required by the Medical Officer of Health for public health reasons. (MoH 2000a). This approach differed from that of the 1984 Standards, because a much wider range of chemical determinands were allocated Maximum Acceptable Values (MAVs), and a procedure was defined which, if followed, would permit a water supplier to demonstrate compliance. This report presents the results of Ministry of Health Programmes that have investigated the chemical quality of community drinking-water supplies. All chemicals that have been identified in community drinking-water supplies at greater than 50% MAV are recommended for classification as ‘Priority 2’. These chemicals are considered to be potentially health significant (and thus require regular monitoring) and are the major subject of this report. The Ministry of Health has formalised Priority 2 classifications made for the larger water supplies (those that serve populations greater than 500). These classifications must be monitored if compliance with the Drinking-water Standards for New Zealand:2000 is to be demonstrated. Assessment of this monitoring has not been investigated, and is not covered in this report. Thus, the information in this report represents an overview of the chemical quality of community drinking-water supplies based only on the data initially used to identify Priority 2 determinands. It is not known if the quality is improving or deteriorating, and an investigation into the monitoring conducted by water suppliers would be required to determine this. Since 1995, a new edition of the Drinking-Water Standards has been introduced – the Drinking-Water Standards for New Zealand:2000 (DWSNZ:2000) (MoH 2000a). This report uses the 2000 version of the Standards as the “yard stick” for assessing the public health significance of the water quality data.


The majority of data used to compile this report have been obtained from the Ministry of Health’s Priority 2 (P2) Identification Programme. Relevant data from surveillance programmes conducted by the Ministry of Health/Department of Health are also included. The Priority 2 Programme is an on-going programme, and the period of time covered in this report is 1995 – 2000. This is termed Phase 1 of the P2 Programme. 859 community drinking-water supplies serving a population of approximately three million people were assessed during this Phase.


CHAPTER 2: METHODOLOGY 2.1 Introduction Ministry of Health national drinking-water programmes investigate community drinking-water supplies that are known to them. The Register of Community Drinking-Water Supplies in New Zealand provides health professionals, drinking-water professionals and the general public with an authoritative summary of the structure of all community drinking-water supplies known to the Ministry of Health. ‘Community drinking-water supplies’ means ‘a publicly or privately owned drinking-water supply which serves more than 25 people for at least 60 days days a year’. A community water supply comprises one or more of each of the following (see Figure 2.1): • The source or raw water: Water that has not received any treatment to make it suitable for

drinking. • The treatment plant: The point where the drinking-water supply enters the distribution

system, regardless of the treatment process. • The distribution system, termed the ‘distribution zone’: The part of the drinking-water

supply network within which all consumers receive drinking-water of identical quality, from the same or similar sources, with the same treatment and usually the same pressure. It is part of the supply network which is clearly separated from other parts of the network, generally by location, but in some cases by the layout of the pipe network. For example, in a large city, the central city area may form one zone, with outlying suburbs forming separate zones or, in a small town, the system may be divided into two distinct areas. The main purpose of assigning zones is to separately grade parts of the system with distinctly different characteristics.

Figure 2.1: Schematic diagram of a drinking-water supply system

RiverSource

Ground-waterSource

LakeSource

TreatmentPlant A

TreatmentPlant B

DistributionZone Y

DistributionZone X

DistributionZone Z

Source: Drinking-Water Standards for New Zealand:2000 (MoH 2000a) The different components of a water supply are listed in the Register, with lines to indicate how they are connected. Water supply distribution zones are categorized by the Ministry of Health, by the populations served. A major zone serves more than 50,000 persons. A large zone serves less than 50,000, but more than 10,000 persons. A medium zone sereves less than


10,000 but more than 5,001 persons. A minor zone serves 501 – 5,000 persons, and a small supply serves 101 - 500 persons. Assessment of the chemical quality of drinking-water by the Ministry of Health focusses on public health significance, and therefore requires samples to be taken from locations that provide a representation of the water quality reaching the consumer (rather than the source water quality). For this reason, results presented in this report relate to chemical quality in the distribution zone ie., at the consumer’s tap, and the populations receiving this water. 2.2 District Health Board areas Ministry of Health public health initiatives are managed regionally by District Health Boards. Each District Health Board will have a contracted Public Health Service Provider (PHSP) that addresses health protection issues. Determinand results are presented as the number of drinking-water distribution zones in which the determinand has been identified, and the populations receiving water from these distribution zones. A map showing the geographical location of all distribution zones registered within the Register of Community Drinking-Water Supplies in New Zealand (MoH 2000b) is presented in Figure 2.2. This report details nationwide results for drinking-water distribution zones, and populations for each chemical determinand listed in the Drinking-Water Standards for New Zealand:2000. The regional results for each determinand are presented in the appendices for each Public Health Service Provider (District Health Board) area. Individuals requiring specific health information about their drinking-water supply should contact their local Public Health Service Provider or their water supplier. 2.3 Surveillance programmes Prior to 1995, the Drinking-Water Standards for New Zealand:1984 (BoH 1984) defined guideline values for microbiological, chemical, and radiological parameters, with the primary aim of protecting public health. Demonstrating compliance with chemical parameters in these standards was not clearly defined. Knowledge about the chemical quality of most drinking water supplies in New Zealand was based on the relatively infrequent sampling undertaken by the Five-, and latterly, Three-yearly Surveillance Programme undertaken by the DSIR (Chemistry Division) and ESR on behalf of the Department of Health. The approach taken by the Five-yearly Surveillance Programme, which ran during the 1980’s was to sample waters from the source water, directly post-treatment, and from the distribution system, and to measure the same parameters in all samples. Only physical and inorganic parameters were initially measured in the Programme. In 1987 a pilot survey of organic contaminants in New Zealand’s drinking-water supplies was undertaken, and in 1989 organic contaminants were routinely incorporated in the Programme. At this stage, the suite of analyses being undertaken was tailored to fit with the sampling location in the system, and with the type of supply (chlorinated, unchlorinated, or school). Many of the results presented in this report are derived from the surveillance programmes described above. In particular, many of the arsenic, boron, fluoride and nitrate results obtained



from data collected through these surveys are relevant to the drinking-water standards in use today, and are therefore included in this report. 2.4 The P2 Programme The P2 Programme methodology is the primary tool used for generation of the data presented in this report. There are approximately 130 chemical determinands listed in the Drinking-Water Standards for New Zealand:2000 (MoH 2000a) as significant to health when present over certain defined levels (Maximum Acceptable Values – MAVs). Those that are actually present in a specific water supply at levels potentially significant to public health (Priority 2) will depend on the characteristics of each supply. Priority 2 determinands are thus supply-specific. Priority 2 determinands are generally those that have been found in a supply at greater than 50% of their MAV in the Priority 2 Chemical Determinand Identification Programme. The Priority 2 Chemical Determinand Identification Programme (the P2 Programme) has the objective of identifying all chemical determinands that should be classified as Priority 2. The main function of the P2 Programme is the provision of an efficient, risk-based approach for the identification of chemicals of potential health significance that should be monitored by water suppliers. The Programme assesses all drinking water supplies serving a population of greater than 100 that are registered in the Ministry of Health’s Register of Community Drinking-Water Supplies in New Zealand (Register). Throughout the Priority 2 Programme, ESR Analytical, and its subsequent owner - AgriQuality, have provided the analytical services necessary for the generation of new analytical data. The stages involved in the assessment of the chemical quality of a drinking-water distribution zone through the P2 Programme are shown in Figure 2.3. Figure 2.3: The stages involved in the assessment of a drinking water supply * The exception to this is for a new category of water – aggressive – introduced in the DWSNZ:2000. Supplies can be designated as “aggressive” but “aggressiveness” cannot be assigned as a P2 determinand.

Information from water suppliers and

PHSPs

Historical water quality information

Baseline sampling

For supplies serving populations greater than 100, if any determinand is present at a concentration of > 50 percent of its MAV, then ESR recommends it to the Ministry of Health as

a P2 determinand*. For supplies serving a population of greater than 500, the Ministry of Health informs the water supplier, and if no valid objection is received, the determinand is classified as

P2. Its classification is included in WINZ and the Register.

Assessment of information to

identify determinands that may be present in a

supply at concentrations

potentially significant to

health.

First monitoring round (M1)

Second monitoring round (M2)


2.5 Sample analysis The P2 Programme assessment process ensures that zones are assessed for all determinands. Samples are collected for analysis for those determinands that are suggested, by the assessment information, to be present in the distribution zone at potentially health significant concentrations. Chemical determinands that are listed in the Standards, are not assessed through collection of samples for analysis in all distribution zones, i.e. a blanket monitoring approach is not taken. This is because collection of historical information along with supply details from the questionnaires used in the P2 Programme permits the targeting of selected determinands for analysis. This means that although 859 distribution zones have been fully assessed through the P2 Programme, there are not 859 sets of analytical data for each determinand. Some determinands have been shown to occur frequently in distribution zones at potentially health significant concentrations, or to have concentrations that vary considerably with time in a distribution zone. In order to minimise the risk that these determinands would not be identified as Priority 2 in the assessment process samples were collected for analysis of these determinands regardless of the assessment information. These determinands were corrosion derived metals (antimony, cadmium, chromium, copper, lead, nickel and tin) and disinfection by-products (for all zones receiving disinfected water). 2.6 Extrapolation of results to multiple zones fed by a single treatment plant The Drinking-water Standards for New Zealand:2000 classifies Priority 2 chemical determinands into different types, as follows: Priority 2a: Chemical and radiological determinands that could be introduced into the drinking-water supply by the treatment chemicals at levels potentially significant to public health (usually greater than 50% MAV). Priority 2b: Chemical and radiological determinands of health significance that have been demonstrated to be in the drinking-water supply at levels potentially significant to public health (usually greater than 50% MAV). Priority 2b determinands are of two main types: Priority 2b, Type 1: substances whose concentration is unlikely to vary during distribution; Priority 2b, Type 2: substances whose concentration may vary during distribution. In New Zealand it is quite common for more than one drinking-water distribution zone to be supplied by a single treatment plant. In this situation it is a waste of resources to analyse for the same Priority 2b, Type 1 determinands in all distribution zones served by the same treatment plant, because the concentrations should be the same. In cases where there is more than one distribution zone served by a single treatment plant, if a Priority 2b, Type 1 determinand has been identified in one distribution zone, it is automatically identified in all the other distribution zones connected to the same treatment plant. This assignment of results to other distribution zones only occurs when all affected zones are served by a single treatment plant, and not in situations where there is more than one treatment plant providing water for distribution zones. The number of distribution zones that have a determinand detected may exceed the number listed as assessed through the P2 Programme, and this can be for the following reasons:


• Some distribution zones may have a chemical identified in their supply on the basis of the duplication of P2b Type 1 determinands described above, but may not have not been assessed through the P2 Programme;

• Some distribution zones may have been assessed through the surveillance programmes, but not the P2 Programme.

2.7 Detection limits and detections Throughout the duration of Phase 1 of the P2 Programme, regular reports have been issued to the Ministry of Health detailing all distribution zones in which determinands have been identified at greater than 50% MAV. The Ministry of Health has only received information relating to determinands identified in a distribution zone at concentrations greater than 50% MAV. Detections below 50% MAV are of interest for three reasons: 1. If a determinand’s concentration in a distribution zone is significantly variable over time,

then the median concentration of a determinand in a distribution zone may be quite different from that obtained from the relatively few results available. The P2 Programme has provided relatively little indication of determinand variability within a zone, because a maximum of only three samples have been taken from any one zone. However, the range of concentrations from all zones provides a larger sample size, from which a general measure of variability of each determinand can be obtained;

2. Concentrations close to, but below, 50% MAV may easily rise above this level in the future;

3. For some determinands, detections can indicate water contamination by poor land use practices, and this is of note to those with responsibility for short and long term resource management.

Care must be taken when examining data relating to all detections rather than solely results greater than 50% MAV, and interpreting the relevance of the information. In all cases where information relating to detections below 50% MAV is presented, the following should be noted: 1. How high is the limit of detection in relation to the MAV? If the limit of detection is low, and the determinand is one that is ubiquitous in nature, then the detection information may relate solely to background levels of no significance to public health. Conversely, if the limit of detection is high, then it is possible that the determinand is present in the supply, below the limit of detection. High limits of detection for chemicals introduced by land use activities can hinder the ability to identify contamination issues when they are minor. 2. Did the limit of detection change over time? When looking at temporal trends in water quality, any changes to the limits of detection are of note, because these may be the reason for a determinand being detected, when previously it was not (if the limit of detection has decreased). 3. Analytical costs have been reduced by excluding samples unlikely to contain the determinand. The P2 Programme uses a targeted approach for monitoring, in order to be able to cost effectively determine the presence of all 130 chemicals listed in the Standards. If information collected about a drinking-water supply indicates that a determinand, if present, is highly unlikely to exceed 50% MAV, then it is not analysed. Thus, information relating to detections is likely to present higher concentrations of determinands than median levels in all


community drinking-water supplies, because samples in those supplies in which the determinand was thought to be least likely to be found are not taken. 2.8 Statistical analysis of the data presented in this report Data presented in this report have been analysed using simple descriptive statistical methods. Inferential statistics (use of the data reported here as a basis for making estimates or predictions) has not been used. Three factors have been important to the decision not to use inferential statistics and to limit the use of descriptive statistics: 1. All analytical information is available relating to samples collected through Phase 1 of the

P2 Programme (not detected, detected at less than 50% MAV, and detected at over 50% MAV). Analytical information from the preceeding surveillance programmes is fragemented and difficult to interpret because of the different sampling locations used. Only values greater than 50% MAV have been used in this report, meaning that the total data set is comprised of two different subsets;

2. Drinking-water in distribution zones has not been analysed for a uniform set of determinands. Monitoring has been targeted to reduce analyses of those determinands that are considered to have the potential to be present in a supply at health significant concentrations. Because of this, interpretation of analytical detections is likely to provide an overestimate of the occurrence of determinands in drinking-water;

3. Detection limits have altered. The project specifications for the P2 Programme indicated that the detection limit for all determinands assessed should be no more than 20% MAV. A lack of detections of chemicals taken during the surveillance programmes may result from the limit of detection being higher than it is today, rather than an absence of the chemical in question.

2.9 Minimum, Median and Maximum concentrations The minimum, median and maximum concentrations have been calculated for all determinands presented in this report. All results that were reported as ‘nd’ (not detected) have been included in these calculations. Therefore minimum concentrations reported as ‘nd’ are less than the limit of detection. 2.10 The relationship between determinands identified >50% MAV and source type The type of source used to supply a distribution zone is of interest to the information presented in this report if it can be shown to have a relationship with the chemicals identified at greater than 50% MAV. When a supply is registered within the Register of Community Drinking-water Supplies in New Zealand, (MoH 2000b) its source, or sources are given unique identifying codes beginning with G, S or R depending on whether they are groundwater, surface water or rainwater. An inappropriate code may be given in certain situations. These are generally where spring waters have been classified as surface rather than ground supplies (because they are not securely abstracted, and therefore may have a surface influence as well as the dominant groundwater influence). The classification of infiltration galleries and shallow wells close to


rivers is also problematic. The potential for these waters to be a mix of both surface water and ground water in these situations can make classification as ‘S’ or ‘G’ quite subjective, and it is likely that some sources of this type have been allocated the wrong code. The error associated with the use of these ‘S’, ‘G’ and ‘R’ codes is acknowledged, but is not considered to be large enough to alter the general findings related to source types that are presented in this report. On occasions it has been possible to identify a relationship between the frequency with which determinands are identified at greater than 50% MAV, and the type of source water used. This has been possible for each determinand through comparison of the results for each source type with the total data set. 2.11 Type of supply When assessing the health significance of a chemical and the strategies required to reduce health significance, it is useful to identify distribution zones that serve schools, because of the vulnerable nature of these consumers, and small supplies because of their smaller financial resources. In this report non-school distribution zones are split into those serving populations of 500 or less, and those serving populations greater than 500. School drinking-water supplies have been identified through use of the ‘owner type’ information listed in WINZ. This has the advantage of picking up those supplies that have names that do not identify them as a school. However, in cases where a community connects to the school supply, these non-school supplies will be incorrectly identified. It is considered that this amounts to a small fraction of the total number of schools and is not of concern in this report. 2.12 Use of the data in this report for small (unassessed) drinking-water supplies One of the objectives of this report is to provide information, or establish guidelines that will assist in identifying possible health significant chemical determinands in distribution zones that have not been assessed for chemical quality. Samples collected for the Ministry of Health Surveillance or P2 Programmes have been collected post treatment or from the consumer’s tap. This has been in an effort to determine the level of public exposure to chemicals, and hence their health significance. The collection of samples from the distribution zone, rather than the source, limits the certainty with which any statements can be made about the water quality of unassessed zones. Source water quality will be altered by the following factors: Treatment: The water from which these distribution zone samples are taken may have been subjected to water treatment processes that can effectively remove some chemicals but may add others. The influence that treatment operations will have on a water will be dependent on the nature of the water and the treatment plant operations. Some treatments to improve the quality of water are cheaper and simpler than others. The removal of manganese, for example, can be cheap and simple. Results presented in this report are therefore highly likely to under-represent the presence of manganese in raw waters. This type of issue is of relevance if the data presented in this report are used to infer water quality issues for unassessed supplies.


Distribution: Distribution of the water to consumers introduces factors of contact time with disinfectants and with the distribution and plumbing components. This is especially important with regards to the concentration of disinfection by-products and corrosion-derived metals (antimony, cadmium, chromium, copper, lead, nickel, tin). The presence of these metals in a water should not be taken to suggest their presence in the source water, unless the sampling location has been exceptionally well flushed. For the reasons outlined above, there are limitations to what can be concluded about zones that have not been assessed, from the data presented in this report.


CHAPTER 3: SYNTHESIS OF KEY FINDINGS, AND PUBLIC HEALTH STRATEGIES

3.1 Introduction This chapter presents the key findings of the report, their implications and suggest possible strategies for public health protection. 3.2 Chemical determinands of high public health significance Of the chemical determinands, or determinand groups, that have been assessed, several stand out as being of high public health significance because they have been identified in a large number of distribution zones or high total population is served by these zones (or both of these factors). The data relating to these chemicals have been assessed more extensively in an effort to identify features that influence their appearance and concentration. The chemical determinands, and determinand groups are: 1. Corrosion-derived metals 2. Arsenic 3. Disinfection by-products 4. Nitrate 5. Manganese A synthesis of the key findings, implications and strategies are presented for these determinands, and determinand groups, in the following five sub-sections. Sub-sections covering the other key findings of this report follow. One factor of over-arching relevance to the chemicals that have been identified at potentially health significant concentrations, is the absence of time series data. This limits interpretation of the variation of chemical concentrations, because the range of concentrations that has been reported is dominated by the influence of geographic variation, rather than variation in a single distribution zone. Time series data are currently being collected by those water suppliers monitoring chemicals in order to demonstrate compliance with the Drinking-Water Standards for New Zealand:2000. A systematic survey to collect this compliance monitoring information on an annual (or regular) basis would allow temporal trends in chemical concentrations to be assessed, providing information on concentration trends of national and local importance. Recommendation: Systematic surveillance of chemical compliance monitoring data (collected by water suppliers), conducted on an annual basis would provide time series data for those supplies with concentrations greater than 50% MAV and serving a population of over 500. This would permit an assessment of the temporal variability of chemical concentrations.


3.3 Corrosion-derived metals 3.3.1 Introduction Corrosion metals include the following metals: antimony, cadmium, chromium, copper, lead, nickel and tin. These metals have all been found in water as a result of contact with distribution pipework and plumbing fittings. They are considered as a group because they have a common factor that is influential to their appearance in drinking-water: corrosive action of the water. The key findings from the corrosion-derived metal results are presented in this section, in terms of the population affected, number and size of distribution zones, and the source types used. Strategies to reduce public exposure to corrosion metals are discussed. 3.3.2 Population affected In terms of the overall number of zones with chemical determinands identified at greater than 50% MAV, the corrosion derived metals is the class of determinands of greatest concern. Corrosion metals have collectively been identified at greater than 50% MAV in distribution zones that supply a population of approximately 860,000. This figure counts any zone in which at least one corrosion-derived metal has been found at more than 50% of its MAV (Nokes and Davies, 2000). Lead is the individual determinand that has been identified in distribution zones at greater than 50% MAV the greatest number of times (323). The total population served by these distribution zones is high (approximately 600,000). The total populations served by distribution zones in which corrosion metals have been identified at greater than 50% MAV are shown in Table 3.1.


Table 3.1 Drinking-water distribution zones with corrosion metals identified at greater than 50% MAV – by distribution zone size

Population size of distribution

zones

Major, large and medium (> 5,000)

Minor (501-5000) Small (101 - 500) Other (< 100) Total

Number of zones

Pop. Number of zones




Pop.

Antimony

Greater than 50% MAV

1 117,100 4 5,157 16 3,878 2 143 23 126,278

Greater than MAV

0 0 1 1,107 4 1,130 1 63 6 2,300

Cadmium


6 97,214 25 39,165 19 3,967 4 263 54 140,609

Greater than MAV

3 33,827 15 25,730 9 1,675 3 238 30 64,750

Chromium


0 0 0 0 1 150 0 0 1 150

Greater than MAV

0 0 0 0 1 150 0 0 1 150

Copper Greater than 50% MAV

2 15,882 21 33,681 36 8,564 9 405 68 55,319

Greater than MAV

0 0 8 10,172 12 2,308 4 225 24 13,405

Lead Greater than 50% MAV

23 406,245 104 165,917 152 37,848 44 2268 323 612,278

Greater than MAV

18 340,734 68 114,226 91 21,301 18 1,053 195 477,314

Nickel Greater than 50% MAV

10 274,176 49 76,911 55 12,484 9 645 123 364,216

Greater than MAV

8 223,995 34 54,709 35 7,685 6 353 83 286,742

Pop. = Population


3.3.3 Conclusions, implications and possible strategies for reducing exposures to corrosion-derived metals in New Zealand drinking waters No. Conclusion Implication Possible Strategies

1 General: Of the seven metals (antimony, cadmium, chromium, copper, lead, nickel and tin) identified as associated with corrosion, all except tin have been identified in distribution zones at concentrations greater than 50% MAV

Tin is not important in public health terms.

2 Chromium: Chromium has been identified at greater than 50% MAV in only one zone.

Chromium is not important in public health terms. Antimony, cadmium, copper, lead and nickel are important in public health terms.

Further investigation of the zone in which chromium was identified may provide information relating to the appearance of chromium.

3 Public exposure, metals > 50% and transgressing MAV: The population and number of distribution zones in which corrosion metals have been identified at greater than 50% MAV, and transgressing the MAV is very high and affects all distribution zone sizes.

- The frequent identification of corrosion derived metals, as a group, is an important public health issue for those served by both large and small distribution zones; - Strategies used to address the issue of heavy metals will be applicable to supplies of all sizes; - There is a reasonable likelihood that corrosion-derived metals will appear in the waters of most zones that have not been assessed, irrespective of their size.

3a) The Ministry of Health has investigated the widespread occurrence of corrosion derived metals in New Zealand community drinking-water supplies (Nokes, 1999a). They have found that the concentration of all corrosion derived metals, with the exception of copper, can usually be effectively reduced by flushing of the tap. This is because elevated concentrations of lead, cadmium, antimony and nickel have most frequently been found to occur as a result of waters lying stagnant in plumbing fittings. The Ministry of Health indicates that in these situations, at least 500ml of water should be flushed from the tap and discarded to flush away corrosion products (MoH 2000a pp.53); 3b) Water can be treated to reduce its corrosiveness; 3c) Long term strategy: improve the quality of metal plumbing fittings.

4 Public exposure, data variability: The concentration of corrosion metals in a distribution zone is dependant on a number of influential factors, which means that concentrations within a zone can and do vary.

The concentration of metals reported for a zone from a sample taken at a single location should not be considered as a definitive guide to their concentration throughout the zone.

The Ministry of Health strategy outlined in 3a should be promoted as a good public health initiative for all of the population.


No. Conclusion Implication Possible Strategies

5 Geographical ‘hot spots’: No geographical trends were apparent for any of the corrosion-derived metals

- Plumbing fittings in all parts of the country are susceptible to dissolution; - Waters corrosive enough to lead to elevated heavy metal concentrations are found all over the country; - There is a reasonable likelihood that corrosion-derived metals will appear in the water of most zones that have not been assessed, irrespective of location.

6 Lead and nickel: Of the corrosion-derived metals (and of all of the determinands assessed in this report), lead and nickel have been identified at health significant and potentially health significant concentrations in the greatest number of distribution zones. These zones serve the highest population.

- Lead and nickel are important in public health terms; - It is important that strategies selected to reduce exposure to heavy metals in general, are effective in reducing exposure to lead and nickel.

See Strategies 3a, b and c.

7 Cadmium and copper: Cadmium and copper have been identified in a high number of distribution zones at concentrations exceeding 50% MAVs, and transgressing MAVs. The zones serve high populations.

Cadmium and copper are moderately important in public health terms.

See Strategies 3a (cadmium only), b and c.

8 Antimony transgressions: Antimony has been identified at concentrations greater than 50% MAV in distribution zones that serve a high population. However, the total population for which antimony exceeds the MAV is relatively low.

Antimony is less important than lead, nickel, cadmium and copper in public health terms.

9 Copper: Copper concentrations are less effectively reduced by flushing.

In situations where water is known to be corrosive, copper and its alloys are not a suitable choice of plumbing material. Materials used for the distribution of drinking-water should be compatible with the water quality.

The strategy defined in 3a (flushing) has been shown to be less effective for copper, because the copper may be sourced from distribution pipework and other fittings that are not associated with taps. Where water in a distribution zone has been identified as having corrosive properties, copper, and its alloys, should not be selected as a plumbing material.



10 Copper & schools: There is a good correlation between the identification of copper at concentrations greater than 50% MAV, and school supplies.

School drinking-water supplies may be especially prone to copper at greater than 50% MAV. This may be for four reasons: 1. Schools may use copper, or its alloys, more

extensively than other distribution zones; 2. School drinking-water may be more

corrosive than that of other drinking-water; 3. Water may be left standing in pipework for

longer periods than it is with other distribution zones;

4. Corrosive water may be less likely to be treated to reduce corrosiveness.

- The strategy defined in 3a (flushing) has been shown to be less effective for copper, because the copper may be sourced from distribution pipework and other fittings that are not associated with taps; - If the residence time of water in the school distribution zone is long, replacement of any copper, or copper alloy pipework and fittings may be appropriate in some circumstances; - The Ministry of Education should be informed of the implications that relate to school supplies.

11 Other metals and schools: There is a correlation between the identification of other corrosion-derived metals (esp. lead) at greater than 50% MAV, and school supplies.

School supplies may be more prone to having corrosion-derived metals in the drinking-water at greater than 50% MAV than other supplies. This may be for three reasons: 1. School drinking-water may be more

corrosive than that of other drinking-water; 2. Water may be left standing in pipework for

longer periods than it is with other distribution zones;

3. Corrosive water may be less likely to be treated to reduce corrosiveness.

- See Strategies 3a, b and c; - If the source is rain-water, strategy 3a will not be effective. In these situations, replacement of roof materials containing lead is a protection strategy; - The Ministry of Education should be informed of the implications that relate to school supplies.

12 Antimony and groundwater: There is a good correlation between distribution zones that have antimony identified at greater than 50% MAV, and the use of groundwater.

Distribution zones that have not been assessed and are fed by groundwater rather than surface sources are more likely to have antimony identified at greater than 50% MAV.

See Strategies 3a, b and c



13 Other corrosion-derived metals and groundwater: There is some correlation between distribution zones that have corrosion metals identified at greater than 50% MAV and the use of groundwater.

- Distribution zones that have not been assessed and are fed by groundwater rather than surface sources may be more likely to have other corrosion-derived metals identified at greater than 50% MAV; - The corrosiveness of groundwaters tends to be greater than that of other water types.

- See Strategies 3a, b and c; - Small communities using, or considering the use of groundwater should be advised of simple measures that can be taken to reduce the corrosiveness of their waters (e.g. addition of limestone or marble chips, or ‘Akdolit’ to their holding tanks.


3.4 Arsenic 3.4.1 Introduction The data presented in this report include 342 samples analysed for arsenic. The elevated arsenic results that have been obtained are generally consistent with areas of known geothermal activity. It is generally accepted that the results presented here relate to arsenic of geothermal origin, although man-made sources such as contamination from sheep dips, timber treatment processing, other pesticides containing arsenic, plus various industrial processes cannot be ruled out. The key findings from the arsenic results are presented in this section, in terms of the population affected, number and size of distribution zones, location of the zones and the source types used. Strategies to reduce public exposure to arsenic are discussed. 3.4.2 Populations affected Distribution zones in which arsenic has been identified at greater than 50% of the MAV serve a total population of 284,720. This total population is spread throughout 70 distribution zones serving the populations shown in Table 3.2. The MAV for arsenic is based on an excess lifetime cancer risk of 6 x 10-4 (one in every 1,700 people). This figure represents use of a level of risk that is higher than for other carcinogens with MAVs. The MAV for all other carcinogens (except bromate) are based on an excess lifetime cancer risk of 10-5 (1 in every 100,000 people). Arsenic has been identified at concentrations greater than its MAV in 28 distribution zones that serve a total population of 21,284. This population is spread throughout distribution zones of various sizes as shown in Table 3.2. Table 3.2 Drinking-water distribution zones with arsenic identified at greater than 50%

MAV – by distribution zone size

Population size of

distribution zones



Number of zones





Pop.


9 248,850 17 27,324 29 7,825 15 721 70 284,720

Greater than MAV

1 10,450 7 8,070 13 2,526 7 238 28 21,284

Pop. = population


3.4.3 Conclusions, implications and possible strategies for reducing exposures to arsenic in New Zealand drinking waters No. Conclusion Implication Possible Strategies

1 Public exposure: The majority (87%) of the population receiving water in which arsenic has been identified at greater than 50% MAV are served by only ten zones.

Improved management (treatment) of these ten zones will result in a large reduction in the population exposed to arsenic at potentially health significant concentrations.

Options are needed to address the specific treatment issues associated with these ten supplies, with a view to decreasing the arsenic concentration of water in the distribution zone. a) See Strategy 3 for the options associated with the four zones using water from Lake Taupo/Waikato River. b) Six of the ten zones use groundwater sources. There is a lack of information relating to the effectiveness of arsenic removal at treatment plants fed by groundwater. This needs to be addressed if the number of distribution zones fed by groundwater and with arsenic at greater than 50% MAV is to be reduced.

2 Surface water regional: There is a strong relationship between distribution zones that have arsenic identified at greater than 50% MAV and the use of water from Lake Taupo or the Waikato River.

Unassessed distribution zones that use water from the Lake Taupo/Waikato River system should be assumed to have arsenic at a concentration greater than 50% MAV, until proven otherwise. Management through treatment of water fed to these zones is therefore likely to be required.

Unassessed zones fed by water from Lake Taupo or the Waikato River can be assumed to have public health issues relating to arsenic. A long term strategy is needed to address this.

3 Surface water treatment: Some assessed distribution zones fed by water from the Waikato River have not had arsenic identified at a concentration greater than 50% MAV.

Either treatment processes in use, or water chemistry at certain locations on the Waikato River have an influence on arsenic concentrations in treated water. Gregor, 2001 found that the ability of a water treatment process to reduce the arsenic concentration in drinking-water is influenced by the concentration of As(III) in the source water.

Review existing effectiveness of treatment of different oxidation states of arsenic in source water to identifying whether the treatment plants are capable of producing water with arsenic at concentrations less than 50% MAV. Priority order: 1. The four zones using water from Lake Taupo/Waikato

River in No. 1 above, 2. All other zones with arsenic identified at greater than

50% MAV that use these sources.



4 Groundwater regional: There is a strong relationship between distribution zones that have arsenic identified at greater than 50% MAV, and the use of groundwater (including springs) in the Pacific Health Rotorua and Pacific Health Whakatane area.

Unassessed distribution zones fed by groundwater in the Pacific Health Rotorua or Pacific Health Whakatane area should be assumed to have arsenic at greater than 50% MAV until proven otherwise. Management through treatment of water fed to these zones is therefore likely to be required.

Use of groundwater resources in the Pacific Health Rotorua and Whakatane areas is exposing these populations to potentially health-significant arsenic concentrations. See Strategy 1b.

5 Groundwater national: There is an absence of Ministry of Health information relating to the geographical extent and magnitude of arsenic concentrations in groundwaters.

It is not known whether the variation in concentrations of arsenic in some of the distribution zones fed by groundwater in the Central Plateau area is caused by treatment processes (unlikely) or lower arsenic concentrations in source water (likely), because MoH samples are taken from the distribution zone rather than source. A study of arsenic concentrations in aquifers in this area would enable ranking of aquifers by arsenic concentration. This could be used to guide future strategies.

Use of groundwater is widespread throughout New Zealand. Arsenic concentrations and oxidation states in the aquifer resources are unknown, and this needs to be addressed if strategies are to be developed.


3.5 Disinfection by-products 3.5.1 Introduction The range of chemical compounds that form as a result of the disinfection of a drinking-water supply is wide. Those chemical compounds with MAVs allocated in the DWSNZ:2000 (MoH 2000a) are: Bromate cyanogen chloride formaldehyde Chlorate dibromoacetonitrile trichloroacetaldehyde/chloral hydrate Bromodichloromethane dibromochloromethane trichloroacetic acid Bromoform dichloroacetic acid trichloroacetonitrile Chlorite dichloroacetonitrile trihalomethanes Chloroform dichloromethane haloacetic acids The key findings from the disinfection by-product (DBP) results are presented in this section, in terms of the population affected, number and size of distribution zones, location of the zones and the source types used. Possible strategies to reduce public exposure to disinfection by-products are discussed.


Table 3.3 Drinking-water distribution zones with disinfection by-products identified at greater than 50% MAV – by distribution zone size

Population size of distribution

zones



Number of zones





Pop.

Bromodichloromethane


0 0 3 7,780 1 300 0 0 4 8,080

Greater than MAV

0 0 0 0 0 0 0 0 0 0

Chlorate


7 409,291 3 9,000 20 5,055 2 180 32 423,526

Greater than MAV

0 0 0 0 7 1,405 1 100 8 1,505

Dichloroacetic acid Greater than 50% MAV

4 37,700 14 25,260 18 5,053 2 110 38 68,123

Greater than MAV

0 0 3 2,600 2 560 0 0 5 3,160

Trichloroacetaldehyde/chloral hydrate Greater than 50% MAV

11 148,620 34 76,232 27 8,177 3 220 75 233,249

Greater than MAV

1 35,700 4 8,210 12 3,065 0 0 17 46,975

Trichloroacetic acid Greater than 50% MAV

1 20,000 11 17,910 11 3,190 0 0 23 41,100

Greater than MAV

0 0 0 0 1 240 0 0 1 240

Haloacetic acids Greater than 50% MAV

7 88,000 31 65,502 27 8,008 6 470 71 161,980

Greater than MAV

2 26,000 13 25,860 13 3,954 0 0 28 55,814

Trihalomethanes Greater than 50% MAV

1 42,000 16 29,803 15 4,140 2 180 34 76,123

Greater than MAV

0 0 1 4,600 1 300 0 0 2 4,900

Pop. = Population


3.5.2 Conclusions, implications and possible strategies for reducing exposures to disinfection by-products in New Zealand drinking waters No. Conclusion Implication Possible Strategies

1 Population general: DBPs have been identified in distribution zones that serve a wide range of population sizes, and affect a large total population.

DBPs are important in public health terms. As a general strategy for reducing DBP concentrations at the operational level, water suppliers with this water quality problem should: • select as source water with a low natural organic matter

content, where this is possible; • use treatment processes, such as those involving

coagulation/flocculation to reduce the concentration of natural organic matter in the water before disinfectants are dosed;

• where a particular DBP is a concern because of the nature of the disinfectant used, a change of disinfectant can be considered.

2 Population, zone sizes: There is no apparent link between the size of distribution zones and the identification of DBPs at greater than 50% MAV, however for some DBPs a few larger zones account for more than half the affected population.

The most important factors that lead to elevated DBP concentrations in water are not linked to distribution zone size. Successful actions to reduce the concentrations of DBPs in the few large supplies with elevated DBP concentrations will reduce the population exposed to these determinands by approximately 50% or better.

Focus attention on reducing the DBP concentrations in the relatively small number of zones with concentrations more than 5,000 in which DBP concentrations are elevated. Success in reducing DBP formation in these zones will result in a reduction of the population exposed to these determinands of 50% or better.



3 Population, chlorate: 1. Considering DBPs only,

concentrations of chlorate that exceed 50% of the MAV affect the largest combined population. The high population is largely the result of a single plant (TP00129) producing elevated levels of chlorate and affecting a number of very large distribution zones.

2. The population served by distribution zones in which chlorate transgresses the MAV is relatively low (1,500 people).

1. Actions taken to reduce the chlorate concentration in water leaving the affected treatment plant will reduce the population exposed to chlorate at concentrations greater than 50% MAV by approximately 80%.

2. The public health importance of chlorate in terms of the total population served by distribution zones in which chlorate transgresses the MAV is not as great as for other disinfection by-products because this population is relatively low.

Investigate the use of hypochlorite (source of supply, storage conditions and period, etc) at the treatment plant feeding the large, affected zones, to identify which practices can be modified to reduce the chlorate concentrations appearing in the treated water. Make water suppliers aware of the factors that are likely to lead to elevated chlorate concentrations in their finished water, so that they can identify which might be leading to their problems. (The factors are well described in the literature and include, storage period and temperature of storage).

4 Population, haloacetic acid family 1. Considering DBPs only, haloacetic

acids at concentrations exceeding the MAV affect the largest population.

2. A large percentage of this population is contained in two of the larger distribution zones.

1. The size of the population exposed to health-significant concentrations of haloacetic acids makes this DBP family of public health importance.

2. Successful actions to reduce the haloacetic acid concentrations in the two large zones with elevated haloacetic acid concentrations will reduce the population exposed to these determinands by a little less than 50%.



5 Population, trichloroacetaldehyde/chloral hydrate: 1. Considering organic DBPs only,

chloral hydrate at concentrations exceeding 50% MAV affect the largest population.

2. A single large zone accounts for approximately three quarters of the population exposed to chloral hydrate concentrations transgressing the MAV.

1. The size of the population exposed to potentially health-significant concentrations of chloral hydrate makes this DBP of public health importance.

2. Successful actions to reduce the chloral hydrate concentration in the single large zone with elevated chloral hydrate concentrations will reduce the population exposed to these determinands by approximately 75%.

6 Population, trihalomethane family: 1. A single large zone accounts for

approximately a half of the population exposed to trihalomethane concentrations exceeding 50% MAV.

2. Trihalomethanes potentially affect a much smaller population than the haloacetic acids and chloral hydrate.

1. Successful actions to reduce the trihalomethane concentrations in the single large zone with elevated trihalomethane concentrations will reduce the population exposed to these determinands by approximately 50%.

2. In terms of the populations affected, the haloacetic acids and chloral hydrate are greater public health concern than the trihalomethanes, despite the trihalomethanes usually being present at higher concentrations.

Pay greater attention to the reduction of chloral hydrate and the haloacetic acid concentrations, than to the reduction of trihalomethane concentrations, as these determinands present a greater public health concern. Steps taken to reduce concentrations of chloral hydrate and haloacetic acids will also reduce trihalomethane concentrations, because much of the pathway by which they are formed is common.

7 Haloacetonitriles (HANs): HANs have not been identified at greater than 50% MAV in any of the distribution zones assessed.

HANs are not important in public health terms.

8 Supply type, schools: DBPs have not been identified at greater than 50% MAV in many school distribution zones.

DBPs are not a major issue for schools because very few schools chemically disinfect their water on a continual basis.



9 Surface water: DBP formation is greater for surface waters than groundwaters. It tends to be greater when the source is a river or stream than when it is a lake or reservoir.

DBPs are more likely to be a public health issue when surface waters are used as the source water than when other source types are used. The type of source water a supply has can be used as a guide for identifying possible P2 determinands in small supplies that have not yet been assessed.

10 Groundwater: DBP formation is lower for groundwaters than for surface waters. Additionally, disinfection of water in distribution zones fed by groundwater is less common than for zones fed by surface sources.

DBPs are less of a public health issue for supplies using groundwaters than for those using surface waters. The type of source water a supply has can be used as a guide for identifying possible P2 determinands in small supplies that have not yet been assessed.

In areas where disinfection by-product formation is high, groundwater may be a good choice of source water, where it is available.

11 Data variability: Dichloroacetic acid, trichloroacetaldehyde /chloral hydrate and trichloroacetic acid have been identified at concentrations below, but close to 50% MAV for a relatively high number of zones.

These DBPs may be potentially health significant for a larger number of zones than indicated in this report.

Addressing factors that lead to disinfection by-product formation is recommended for all distribution zones in which detections have been found.

12 Geographical ‘hot spots’: DBPs are detected most frequently in south east Otago, Wellington and Manawatu, Taranaki, central North Island and through the Waikato up to Auckland and the Western Bay of Plenty. Disinfection by-product concentrations are seldom elevated in Canterbury and Hawkes Bay (where groundwater is the predominant source water).

The geographic distributions are likely to reflect the nature of the source waters in these areas.



13 Disinfection using ozonation and chlorine dioxide: bromate and formaldehyde are DBPs formed through use of ozonation as a disinfectant. Chlorite is a DBP formed through use of chlorine dioxide as a disinfectant. These determinands have not been assessed for many distribution zones because of the very small number, or absence, of supplies using these disinfection methods.

The public health significance of bromate, formaldehyde and chlorite is low, because the number of zones using disinfection methods that may lead to them are low, and the size of these supplies small, and the concentrations of the DBPs have been undetectable.

14 MAVs: A number of disinfection by-products, for which there are no MAVs, have been identified in distribution zones.

The public health significance of the concentrations of these DBPs cannot presently be assessed because of absence of MAVs.

Maintain a watch on the international literature, and guideline assignments by WHO, so that the health significance of these DBPs can be assessed when the required information becomes available.


3.6 Nitrate 3.6.1 Introduction The data presented in this report include 673 samples analysed for nitrate. The key findings from the nitrate results are presented in this section, in terms of the population affected, number and size of distribution zones, location of the zones and the source types used. Strategies to reduce public exposure to nitrate are discussed. The presence of nitrate in community drinking-water supplies stands on its own as a public health issue for New Zealand. This is because it is the only chemical that has been identified at potentially health significant concentrations (greater than 50% MAV) in a significant number of distribution zones (50) that is sourced from land use-activities. These zones serve a large total population. Better management of land-use activities that lead to nitrate in drinking-water is required. 3.6.2 Population affected Distribution zones in which nitrate has been identified at greater than 50% of the MAV serve a total population of 102,264. This population is spread throughout distribution zones serving populations as shown in Table 3.4. The populations of three distribution zones comprise 90% of the total. These three zones are: • Kitchener PUK002KI Auckland Healthcare Population 11,500 • Richmond RIC002RI Nelson Marlborough Hlth (Nels) Population 10,500 • North-West Christchurch CHR001NW Crown Public Health (Chch) Population 70,000 Table 3.4 Drinking-water distribution zones with nitrate identified at greater than 50%

MAV – by distribution zone size

Population size of

distribution zones

Major, large and medium (> 5000)


Number of zones





Pop.


3 92,000 3 5,012 18 3,806 26 1,446 50 102,264

Greater than MAV

0 0 0 0 4 897 2 120 6 1,017

Pop. = Population


3.6.3 Conclusions, implications and possible strategies for reducing exposures to nitrate in New Zealand drinking waters No. Conclusion Implication Possible Strategies

1 Population (50% MAV): The majority (90%) of the population receiving water in which nitrate has been identified at greater than 50% MAV are served by three zones.

Improved resource management, or a change of source waters for these three zones could result in a large reduction in the population exposed to nitrate at potentially health significant concentrations.

Those with responsibility for resource management should address the nitrate concentrations in these three zones, and take measures to ensure a reduction to nitrate loading, or a replacement of the source waters used.

2 Population (transgressions): The total population served by distribution zones in which nitrate has been identified at concentrations greater than the MAV is low.

Nitrate concentrations are of direct public health concern for a small population at present.

Compliance monitoring data should be periodically collected and reviewed to determine whether nitrate concentrations in an area are increasing. Periodic checks should also be made for trends in nitrate concentrations in supplies in which nitrate concentrations were identified at less than 50% MAV.

3 Groundwater: There is a strong relationship between distribution zones that have nitrate identified at greater than 50% MAV, and the use of groundwater.

Distribution zones fed by groundwater are more likely to contain nitrate at potentially health significant concentrations.

Unassessed distribution zones that use groundwater should be tested for nitrate.

4 Small supplies: There is a strong relationship between the identification of nitrate at greater than 50% MAV and the small size of a distribution zone (less than 500).

- Small supplies are more likely than large supplies to contain nitrate at potentially health significant concentrations;

- Water suppliers for small distribution zones may be less able to influence poor resource management that leads to nitrate contamination;

- Small rural supplies are more likely to be surrounded by agricultural activities that could lead to elevated nitrate concentrations.

- Unassessed distribution zones that serve small populations should be tested for nitrate;

- Water suppliers for small distribution zones should receive an information package to assist in production of PHRMPs for their raw waters.

5 School supplies: There is a strong relationship between the identification of nitrate at greater than 50% MAV and school supplies.

School supplies are more likely to contain nitrate at potentially health significant concentrations.

- Unassessed school supplies should be tested for nitrate;

- The Ministry of Education should be informed of the nitrate results presented in this report, so that they can take action to address land-use activities that may be causing elevated nitrate concentrations in school supplies;

- School suppliers should receive an information package to assist in production of PHRMPs for their raw waters.



6 Geographical ‘hot spots’: No geographical trends were apparent for nitrate.

Groundwaters in any part of the country may contain elevated nitrate concentrations.

7 Data trends: The range of national results for nitrate is wide. No data are available for variability of nitrate in individual distribution zones and so no trends can be established. This limits the ability to determine the impact that certain land uses are having on nitrate concentrations in given conditions.

Changes in land use in New Zealand that may increase nitrate loading to aquifers (e.g. agricultural activity, on-site sewage disposal) represent a public health risk. The risk to the public depends upon the vulnerability of the aquifers to contamination, and the specifications of the groundwater abstraction point. The increase in dairy farms, including stocking density and irrigation, and the increase in life-style blocks with on-site groundwater abstraction and sewage disposal is relevant in this regard.

- Submissions by Health Protection Officers against applications for resource consents likely to increase nitrate loading of aquifers should be encouraged, and reassessments of distribution zones for nitrate should be conducted as necessary.

- Make relevant Ministries (Ministry for the Environment and Ministry of Agriculture and Forestry) aware of the nitrate results presented in this report, so that they can implement strategies relevant to their function.


3.7 Manganese 3.7.1 Introduction The data presented in this report include 400 samples analysed for manganese. The key findings from the manganese results are presented in this section, in terms of the population affected, number and size of distribution zones, location of the zones and the source types used. Strategies to reduce public exposure to manganese are discussed. 3.7.2 Population affected Distribution zones in which manganese has been identified at greater than 50% of the MAV serve a total population of 10,210. This relatively low population is spread throughout 23 distribution zones serving the populations shown in Table 3.5. Small distribution zones (serving populations of 101 – 500) are the primary size category that have manganese identified at greater than 50% MAV. It is considered that two factors may contribute to this: 1. The ease with which manganese can be treated – by simple oxidation techniques –

suggests that it is likely that major, large, medium and minor distribution zones will receive water that has undergone this treatment to reduce manganese concentrations, if this is required;

2. Manganese becomes available under anaerobic/reduced conditions, and small distribution zones may be more likely to use oxygen-deficient source waters.

The ease with which manganese can be treated in many cases suggests that, for community drinking-water supplies at least, it could easily be removed as a public health issue. Table 3.5 Drinking-water distribution zones with manganese identified at greater than

50% MAV – by distribution zone size

Population size of

distribution zones

Major, large and medium (> 5000)


Number of zones





Pop.


0 0 2 5,600 14 4,035 7 575 23 10,210

Greater than MAV

0 0 1 600 3 751 2 200 6 1,551

Pop. = Population


3.7.3 Conclusions, implications and possible strategies for reducing exposures to manganese in New Zealand drinking waters No. Conclusion Implication Possible Strategies

1 Population: The population and number of distribution zones in which manganese has been identified at greater than 50% MAV is relatively low. The number of zones in which manganese transgresses the MAV is also low.

The management of drinking-water supplies to reduce manganese concentrations should take a lower priority than the reduction in concentration of chemicals that affect larger populations.

2 Groundwater: There is a strong relationship between distribution zones that have manganese identified at greater than 50% MAV, and the use of groundwater.

Distribution zones receiving water from groundwater sources are more likely to contain manganese at potentially health significant concentrations.

Unassessed distribution zones that use groundwater should be tested for manganese.

3 Geographical ‘hot spots’: No geographical trends were apparent for manganese.

4 Small supplies: There is a strong relationship between the identification of nitrate at greater than 50% MAV and the small size of a distribution zone (less than 500)

This relationship may result from the treatment of larger supplies to remove manganese, where this is necessary.


3.8 Chemical determinands that have been assessed and identified above 50% MAV in distribution zones that serve a low population

Some of the chemicals reported here have been assessed and identified at concentrations greater than 50% MAV but the number of zones is low, and they serve a low population. These results present management issues for those responsible for the distribution zones in question, but strategies for reducing public exposure to these chemicals are of a lower priority than for chemicals affecting larger populations. These ‘low priority’ chemicals are listed in Table 3.6. Table 3.6 Chemicals identified at greater than 50% MAV in distribution zones that

serve low total populations

Chemical group Chemicals

Inorganics Barium, boron, fluoride, mercury, selenium

Disinfection by-products Chloroform

Pesticides Dieldrin

‘Other organics’ Di(2-ethylhexyl)phthalate

3.9 Chemical determinands that have been assessed and not identified above 50%

MAV in any distribution zones Of the chemicals that have been assessed, those that have not been identified at concentrations greater than 50% MAV in any of the distribution zones that have been assessed are shown in Table 3.7. Table 3.7 Chemicals that have never been detected at greater than 50% MAV in

distribution zones Chemical group Chemicals

Inorganics Beryllium, cyanide, molybdenum, nitrite, silver, tin, uranium

Disinfection by-products Bromate*, bromoform, cyanogen chloride*, dibromoacetonitrile dibromochloromethane, dichloroacetonitrile, dichloromethane, formaldehyde*, trichloroacetonitrile

Pesticides All except dieldrin

‘Other organics’# All except di(2-ethylhexyl)phthalate * limited analytical information # ‘other organics’: organic compounds that are not covered within disinfection by-products, algal toxins and pesticide groups. Some chemicals that have been detected at a concentration below 50% MAV are of interest to those with responsibility for land use activities, because they indicate contamination from land-use activities. These chemicals generally belong within the pesticides and ‘other organics’ groups. Chemicals from these groups that have been detected below 50% MAV are shown in Table 3.8.


Table 3.8 Pesticides and ‘other organics’ detections in distribution zones


Pesticides Simazine, 2,4,5-T, terbuthylazine, triclopyr

‘Other organics’* Acrylamide, benzene, di(2-ethylhexyl) phthalate#, 1,4-dichlorobenzene, ethylbenzene, fluoranthene, tetrachloroethene, toluene, 1,1,1-trichloroethane, trichloroethene, xylenes

*’other organics’: organic compounds that are not covered within disinfection by-products, algal toxins and pesticide groups # also detected in one zone at greater than 50% MAV 3.10 Chemical determinands that have not been assessed Of the 133 determinands that are allocated MAVs in the Drinking-Water Standards for New Zealand: 2000 (MoH 2000a), 98 have been assessed. Those that have not been assessed in community drinking-water supply distribution zones are shown in Table 3.9. Table 3.9 Chemicals that have not been assessed in community drinking-water supplies


Inorganics Aggressiveness*, lithium, chlorine

Disinfection by-products Chlorite, monochloramine (needs to be measured in the field)

Pesticides Azinphos methyl, bromacil, carbofuran, chlortoluron, cyanazine, diquat, diuron, hexazinone, isoproturon, metalaxyl, metribuzin, oryzalin, oxadiazon, picloram, pirimisulfuron methyl, propazine, pyridate, thiabendazole

Algal toxins Anatoxin-a (as STX-eq), anatoxin-a(S), cylindrospermopsin, homoanatoxin-a, LPS endoxins, microcystins, nodularin, saxitoxins

‘Other organics’ EDTA, epichlorohydrin, nitrilotriacetic acid, total PAH mixture *Aggressiveness: Whilst aggressiveness is not a chemical itself, assessment of its level in drinking-water is made through chemical analysis.


CHAPTER 4: INORGANICS

4.1 Introduction This chapter reports on detections of inorganic chemicals in New Zealand’s community drinking-water supplies. Inorganic chemicals are loosely defined as those that are not compounds of carbon, although some compounds containing carbon are included in this definition – cyanide is an example, and is listed in this chapter. Twenty nine inorganic determinands are allocated Maximum Acceptable Values (MAVs) or provisional Maximum Acceptable Values (PMAVs) in Table 14.2 of the Drinking-Water Standards for New Zealand:2000 (DWSNZ:2000) (MoH 2000a). Twenty four are considered in this chapter, whilst bromate, chlorate, chlorite, cyanogen chloride and monochloramine are covered in Chapter 5: Disinfection By-products (DBPs). Three determinands (aggressiveness, lithium and chlorine) are considered in this chapter, but have not been assessed, giving a total of twenty one determinands that have been assessed. Phase 1 of the P2 Programme covered the period 1995 – 2000. During this time, the version of drinking water standards in use was the Drinking-Water Standards for New Zealand:1995 (DWSNZ:1995) (MoH 1995). The following changes are seen in the DWSNZ:2000 New inorganic determinands with MAVs: Aggressiveness

Lithium Introduction of MAVs for determinands previously listed without them

Beryllium: 0.004 mg/L Silver: 0.02 mg/L Tin: 1 mg/L Uranium: 0.002 mg/L

Altered MAVs: Boron 0.3 mg/L to 1.4 mg/L 4.2 Origins of the analytical data 4.2.1 Surveillance Programmes Prior to the P2 Programme, water samples had been taken for public health surveillance purposes through Ministry of Health/Department of Health Surveillance Programmes run by the Ministry of Health. It is understood that factors which influenced the range of analytes tested included the drinking-water standards in use at the time (Drinking-Water Standards for New Zealand: 1984), plus a range of parameters that provided indications of the general chemistry of the water. Inorganic determinands of health significance that are listed in the Drinking-Water Standards for New Zealand:1984 (BoH 1984) are listed in Table 4.1.


Table 4.1 Inorganic determinands of health significance listed in the DWSNZ:1984 (BoH 1984)

Determinand Guideline value – mg/L

Arsenic 0.05 Boron 0.5 Cadmium 0.005 Chromium 0.05 Cyanide 0.1 Fluoride 0.9-1.1 Lead 0.05 Mercury 0.001 Nitrate 10 (nitrate-N) Selenium 0.01

Results for arsenic, boron, fluoride, lead and nitrate, as well as copper (which has an aesthetic guideline value) taken during the surveillance programmes comprise a significant number of the total results reported in this chapter at greater than 50% of the MAV. The P2 Programme, which followed the surveillance programmes, continued to assess community drinking-water supplies for the inorganic determinands listed in Table 4.1, and extended the range assessed, in accordance with the requirements of the DWSNZ:1995, which superseded the DWSNZ:1984. 4.2.2 P2 Programme Baseline sampling The analytical suite conducted from the Baseline sampling round consists of the inorganic and physical determinands listed in Table 4.2. Table 4.2 Analytical suite of the ‘Baseline’ sampling round of the P2 Programme Distribution System Determinands pH Cadmium Alkalinity Chromium Conductivity Copper (added in the 1999/00 Programme Round) Turbidity Lead Calcium Manganese (added in the 1999/00 Programme Round) Cyanide (for unchlorinated zones only) Molybdenum Fluoride (added in the 1999/00 Programme Round) Nickel Antimony Selenium Arsenic (added in the 1999/00 Programme Round) Silver Barium Tin Beryllium Uranium Boron (added in the 1999/00 Programme Round) Source Determinands Antimony Lead Cadmium Nickel Chromium Tin Copper (added in the 1999/00 Programme Round)


Since the start of the P2 Programme, Health Protection Officers have registered many drinking-water supplies in the Register of Community Drinking-Water Supplies in New Zealand (MoH 2000b). Because there is usually no historical information available for these newly registered supplies, it was decided that from the 1999/00 Programme Round onwards the range of inorganic determinands included in the Baseline suite should be extended. The determinands added to the Baseline suite were: fluoride, arsenic, boron, copper and manganese. All of these were added to the suite of determinands for the samples taken from the distribution system, with copper also added to the determinands measured in samples taken from the source. The determinands are shown in Table 4.2. 4.2.3 P2 Programme M1 and M2 rounds of sampling Following the Baseline Sampling Round, two further rounds of sampling are conducted for each supply that is assessed in the P2 Programme. These are termed the M1 and M2 monitoring rounds (first and second monitoring rounds). These rounds differ from the Baseline sampling round because they are targeted to include a much wider range of determinands - all the determinands listed in the DWSNZ:1995 that are considered to potentially be present in the water supply at health significant concentrations. During the first year of the Programme, corrosion metals were included in the Baseline suite for all supplies, but they were not included in the two monitoring rounds unless there was evidence from the Baseline analytical results to indicate that they were a potential problem. Following the 1995/96 year, analysis of a suite of corrosion metals, containing antimony, cadmium, chromium, copper, lead, nickel and tin, has been carried out for samples taken from all drinking-water distribution zones in the Baseline sampling and in both monitoring rounds. The assessment of these metals in all distribution zones was considered necessary when it became evident during the 1995/96 Programme Round that the appearance of heavy metals was widespread and highly variable within a supply. 4.2.4 Fluoride The Ministry of Health uses two different approaches to manage fluoride in drinking-water: 1. If it is intentionally added at the treatment plant, for oral health reasons, it is

automatically classified as P2a for all distribution zones receiving water from that treatment plant. This is because the fluoride content recommended for drinking-water by the Ministry of Health for oral health reasons is 0.7 – 1.0 mg/L and the MAV for fluoride is 1.5 mg/L. There is no requirement for assessment through the P2 Programme and the water supplier must monitor for fluoride as directed by the DWSNZ:2000 if they are to demonstrate compliance;

2. When present as a mineral or contaminant in the source water it is classified as Priority 2b if identified at a concentration greater than fifty per cent of its MAV. Assessment through sampling is required to identify fluoride derived from the source water.

4.3 Summary of results


Table 4.3 presents a summary of results collected for each inorganic determinand covered in this chapter. Further details relating to each determinand can be found by referring to the page dedicated to it. Table 4.3 Summary table for inorganic determinands = Yes = No Determinand name MAV

mg/L Assessed Detected > 50% MAV Transgression

Antimony 0.003 111 zones 23 zones 6 zones Aggressiveness Arsenic 0.01 152 zones 70 zones 28 zones Barium 0.7 592 zones 4 zones 1 zone Beryllium 0.004 62 zones Boron 1.4 129 zones 8 zones 3 zones Cadmium 0.003 188 zones 54 zones 30 zones Chlorine (free) 5 Chromium 0.05 80 zones 1 zone 1 zone Copper 2 832 zones 68 zones 24 zones Cyanide (total) 0.08 1 zone Fluoride 2a* 1.5 N/A 120 zones N/A Fluoride 2b 1.5 44 zones 3 zones 1 zone Lead 0.01 731 zones 323 zones 195 zones Lithium 0.9 Manganese 0.5 286 zones 23 zones 6 zones Mercury (total) 0.002 3 zones 1 zone Molybdenum 0.07 35 zones Nickel 0.02 551 zones 123 zones 83 zones Nitrate 50 (11.29 as

nitrate-N) 529 zones 50 zones 6 zones

Nitrite 3 (0.91 as nitrite-N) until Dec. 1998

5 zones

Selenium 0.01 35 zones 2 zones Silver 0.02 14 zones Tin 1 60 zones Uranium 0.002 *Fluoride 2a classifications are made for all zones that receive fluoridated water. There is no need to assess these zones, because 2a classifications are automatic in these situations. Analysis for nitrite was halted in December 1998 due to changes in the preservation method used by ESR Analytical (now AgriQuality), and resulting sampling complications. All detections of nitrite had been significantly below 50% MAV, so ceasing analysis was not considered to compromise identification of potentially health significant concentrations.


4.4 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV)

Twenty-one inorganic determinands have been assessed. Transgressions of the MAV were identified in one or more drinking-water distribution zones for twelve of the twenty-one determinands. Concentrations that exceeded 50% of the MAV were detected in one or more zones for fourteen of the twenty-one determinands. The populations served by these distribution zones are detailed in Table 4.4. Table 4.4 Inorganic determinands detected at greater than 50% MAV or transgressing

their MAV Determinand Identified at greater than 50% MAV Identified at greater than MAV

Number of zones Population Number of zones Population

Corrosion derived

metals (NB may be more

than one metal

identified in a zone)

Antimony 23 126,278 6 2,300

Cadmium 54 140,609 30 64,750

Chromium 1 150 1 150

Copper 68 55,319 24 13,405

Lead 323 612,278 195 477,314

Nickel 123 364,216 83 286,742

Arsenic 70 284,720 28 21,284 Barium 4 287 1 30 Boron 8 3,372 3 1,225

Fluoride 2a* 120 1,893,344 N/A N/A Fluoride 2b* 3 1,465 1 63

Manganese 23 10,210 6 1,551 Mercury 1 100 0 0

Nitrate 50 102,264 6 1,017 Selenium 2 502 0 0

*Fluoride 2a = Intentionally added at the treatment plant, fluoride 2b = Naturally occurring fluoride. Fluoride 2a – the intentional addition of fluoride at the treatment plant, for oral health reasons - affects the largest population (approximately 1.9 million). In terms of the overall number of zones with inorganic determinands identified at greater than 50% MAV, the corrosion derived metals is the class of determinands of greatest concern. Corrosion metals have collectively been identified at greater than 50% MAV in distribution zones that supply a population of approximately 860,000. This figure has been derived from calculations that remove the double counting that arises when more than one corrosion-derived metal has been found at more than 50% of its MAV in a zone (Nokes and Davies, 2000). Figure 4.1 indicates the relative importance of each chemical that has been identified at greater than 50% MAV, in terms of the total population (Fluoride 2a excluded).


Figure 4.1: Populations served by distribution zones in which inorganic determinands have been identified in their drinking-water supply at greater than 50% Maximum Acceptable Value

*Fluoride 2b = Naturally occurring fluoride. The Ministry of Health has investigated the widespread occurrence of corrosion derived metals in New Zealand community drinking-water supplies (Nokes, 1999a). They have found that the concentration of all corrosion derived metals, with the exception of copper, can usually be effectively reduced by flushing of the tap. This is because elevated concentrations of lead, cadmium, antimony and nickel have most frequently been found to occur as a result of waters that lie stagnant in plumbing fittings. The Ministry of Health indicates that in these situations, at least 500ml of water should be flushed from the tap and discarded to flush away corrosion products (MoH 2000a pp.53). Of the inorganic determinands that are not corrosion derived metals, arsenic and nitrate have been found to have the greatest potential public health significance. The population receiving drinking-water from distribution zones in which arsenic has been identified at greater than 50% MAV is of most concern (population of approximately 285,000), and the zones in which arsenic has been identified at concentrations transgressing the MAV serve a population of approximately 21,000. 4.5 Detections to 50% MAV With the exception of uranium, all of the inorganic determinands that were assessed in the P2 Programme were detected in one or more zones. The large number of detections can be attributed in part to the relatively low limits of detection for inorganic determinands, combined with the naturally ubiquitous presence of many in the environment.


The seven inorganic determinands for which there were no sample results recorded at concentrations greater than 50% of the MAV are: Beryllium Cyanide Molybdenum Nitrite Silver Tin Uranium A relatively high number of samples were taken for all seven of these determinands providing a good sample size. None have shown unusual patterns of concentrations, and all maximum values were well below 50% of their respective MAVs. Because of this it is considered that drinking-waters of a similar nature to those reported here would not be likely to have these determinands present at potentially health significant concentrations. 4.6 Geographical distribution The geographical distributions of determinand results have been plotted using ArcView GIS 3.2 for all those determinands detected in more than fifteen zones. These plots provide a visual presentation of all detections from the P2 Programme, along with any determinands identified at greater than 50% MAV in the surveillance programmes that preceded the P2 Programme. In order to determine any patterns of geographical distribution of inorganic determinands at potentially health-significant concentrations, the number of samples taken, and the number of detections at greater than 50% MAV have been recorded for each Public Health Unit area. This information is presented for each determinand in Appendix 1. With the exception of arsenic, there is a general absence of clear relationships between geographical area and determinand occurrence at greater than 50% MAV. Detections of boron appear to have a degree of geographical dependance (North Island), but if results are restricted to those that are potentially health significant (>50% MAV) then this cannot be seen. 4.7 Source types The distribution zones in which detections of determinands at greater than 50% MAV have been found were investigated to determine whether their source type (rain, surface, groundwater) had any relationship with detections. Relationships with use of groundwater were noted for antimony, manganese and nitrate. 4.8 Gaps in the information Aggressiveness, lithium and chlorite have not been assessed (and chlorine needs to be assessed in the field).


4.9 Antimony 4.9.1 Summary information Maximum Acceptable Value (MAV) 0.003 mg/L

50% MAV 0.0015 mg/L

Remarks (from DWSNZ:2000) None

Assessed in the P2 Programme? Yes: All B, M1 & M2

Limit of detection for samples taken as part of the P2 Programme 0.0005 mg/L (17% of MAV)

Total number of samples analysed for this determinand in Phase 1 of the P2 Programme 897 samples

Number of community drinking-water zones with antimony identified at > 50% MAV 23

Population served by community drinking-water zones with antimony identified at greater than 50% MAV

126,278

Population served by community drinking-water zones with antimony identified at greater than MAV, i.e. health significant concentrations

2,300 (6 zones)

Range of P2 Programme results nd – 0.012 mg/L

Median of P2 Programme results nd

Do the data suggest that antimony is found more frequently in surface, ground or rain water

Yes, 70% of results >50% MAV are from zones using groundwater only (see Appendix

1.1, Table 1.2)

Do the data suggest that antimony is found more frequently in large, small or school supplies

No

4.9.2 Detections up to 50% MAV Antimony was detected in 111 zones (13% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for antimony. 4.9.3 Supporting information Summarized results for antimony are presented for each Public Health Unit in Appendix 1.1.

Number of detections to 50% MAV

0

10

20

30

40

0-10% -20% -30% -40% -50%

per cent of MAV



4.10 Aggressiveness 4.10.1 Summary information Maximum Acceptable Value (MAV) N/A

50% MAV N/A

Remarks (from DWSNZ:2000) Any heavy metal has elevated concentration in first flush sample

Assessed in the P2 Programme? No

Limit of detection for samples taken as part of the P2 Programme N/A

Total number of samples analysed for this determinand in Phase 1 of the P2 Programme 0 samples. Aggressiveness is derived from heavy metals results

Number of community drinking-water zones with aggressiveness identified at > 50% MAV

N/A

Population served by community drinking-water zones with aggressiveness identified at greater than 50% MAV

N/A

Population served by community drinking-water zones with aggressiveness identified at greater than MAV, i.e. health significant concentrations

N/A

Range of P2 Programme results N/A

Median of P2 Programme results N/A

Do the data suggest that aggressiveness is found more frequently in surface, ground or rain water

N/A

Do the data suggest that aggressiveness is found more frequently in large, small or school supplies

N/A

Comment Aggressiveness has not been assessed.


4.11 Arsenic 4.11.1 Summary information

Maximum Acceptable Value (MAV) 0.01 mg/L

50% MAV 0.005 mg/L

Remarks (from DWSNZ:2000) For excess lifetime skin cancer risk of 6 x 10 –4 PMAV, because of analytical difficulties

Assessed in the P2 Programme? Yes: M1 and M2 by selection. Added to

Baseline suite from Programme Round 1999/00 onwards



Number of community drinking-water zones with arsenic identified at > 50% MAV 70

Population served by community drinking-water zones with arsenic identified at greater than 50% MAV

284,720

Population served by community drinking-water zones with arsenic identified at greater than MAV, i.e. health significant concentrations

21,284 (28 zones)



Do the data suggest that arsenic is found more frequently in surface, ground or rain water

No

Do the data suggest that arsenic is found more frequently in large, small or school supplies

No

4.11.2 Detections up to 50% MAV Arsenic was detected in 152 zones (18% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for arsenic. The frequency distribution graph for arsenic, shows a peak of detections at 10% MAV, which is the limit of detection. This indicates that arsenic would be detected more frequently if the limit of detection were to decrease. There is a gradual decline in the number of detections as 50% of MAV is reached, indicating that for arsenic, most results are comfortably below 50% MAV, and it would take a large increase to push them over this concentration.


0

10

20

30

40

50

0-10% -20% -30% -40% -50%

per cent of MAV


4.11.3 Transgressions The MAV for arsenic is based on an excess lifetime cancer risk of 6 x 10-4 (one in every 1,700 people). This figure represents a level of risk that is higher than for other carcinogens with MAVs. The MAV for all other carcinogens (except bromate) are based on an excess lifetime cancer risk of 10-5 (1 in every 100,000 people). Approximately half of the population receiving drinking-water in which arsenic has been identified at a concentration exceeding its MAV, reside within one zone – Cambridge (CAM001CA). The high levels of arsenic as As(III) rather than As(V) has been noted as influential in the final concentrations for this supply (Gregor, 2001). The other half of the population are served by minor, small or ‘other’ (population less than 100) drinking-water distribution zones. The small size of these supplies may be a limitation to their ability to treat the water to reduce arsenic concentrations. 4.11.4 Geographic hot spots Arsenic detections have been found to have a geographic relationship.

Figure 4.2 Detection of arsenic in distribution zones, presented by region (Arsenic results in each region are presented as a percentage of the total number of distribution zones from which samples were taken for

arsenic analysis)

4.11.4.1 The Lake Taupo/Waikato River system – general points Analysis of the results for arsenic in drinking-water distribution zones has identified a number of ‘hot spot’ areas in which the identification of arsenic at greater than 50% MAV has occurred more frequently. The most important ‘hot spot’ is the Lake Taupo and Waikato River area. With regard to the number of distribution zones, and the total populations affected, four points can be made: • Thirty-one (44%) of the seventy distribution zones in which arsenic has been identified at greater than 50%

MAV are connected to the Lake Taupo/Waikato River system. There are only four other distribution zones affected by arsenic at this level that use surface water;

• The remaining thirty-five (50%) of the seventy distribution zones are served by groundwater sources. • The Lake Taupo/Waikato River system provides the vast majority - 91% - of the surface water sources

serving distribution zones in which arsenic has been identified at greater than 50% MAV; • These distribution zones serve a total population of 159,060, which is 56% of the total population served by

zones in which arsenic has been identified at greater than 50% MAV.

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

Northla

nd H

ealth

Auckla

nd H

ealth

care

Health

Waik

ato

Pacific

Hea

lth - T

auran

ga

Pacific

Hea

lth - R

otorua

Pacific

Hea

lth - W

haka

tane

Tairaw

hiti H

ealth

care

Tarana

ki Hea

lthca

re

Health

care

Hawke

s Bay

MidCen

tral H

ealth

- PN

MidCen

tral H

ealth

- Wan

ganu

i

Wairara

pa H

ealth

Hutt Vall

ey H

ealth

Nelson

Marl

borou

gh H

ealth

- Nels

on

Nelson

Marl

borou

gh H

ealth

- Blen

heim

Crown P

ublic

Health

- Chri

stchu

rch

Crown P

ublic

Health

- Wes

t Coa

st

Crown P

ublic

Health

- Tim

aru

Public

Health

South

- Dun

edin

Public

Health

South

- Inve

rcargi

ll

Per c

ent d

etec

tions

>50% MAVDetected


The Lake Taupo/Waikato River system extends through an area covered by four District Health Boards. Because the results present different issues in each of these areas, they are discussed separately. 4.11.4.2 Health Waikato Arsenic has been detected in 32 of the 91 distribution zones assessed in the Health Waikato area. Of these, the concentration of arsenic was greater than 50% MAV in 19 zones. These serve a total population of 136,967. These distribution zones are supplied by source water as follows: • 3 groundwater only • 1 groundwater and surface water mix • 15 surface water only All fifteen of the surface waters, plus the surface water in the mixed source are taken from various abstraction points along the Waikato River. The three groundwater sources are located in the Coromandel Peninsula. Issues for the Health Waikato areas are as follows: The relationship between use of water from the Waikato River and the identification of arsenic at greater than 50% MAV is clear. However, there are several assessed distribution zones that use water from the Waikato River that have not had arsenic identified at greater than 50% MAV. The effectiveness of the treatment processes that remove arsenic are the most likely reason for this (see Gregor, 2001). Distribution zones that are served by groundwater sources appear to be less affected by arsenic in this area. 4.11.4.3 Pacific Health Rotorua Arsenic has been detected in all 44 distribution zones that have been assessed in the Pacific Health, Rotorua area. Of these, the concentration of arsenic was greater than 50% MAV in 36 of the 44 zones. These serve a total population of 77,309. The distribution zones are supplied by source water as follows: • 18 groundwater only • 1 roof water only (this result may represent an error in the registration details for the zone) • 17 surface water only Of the 17 distribution zones using surface water, 15 (88%) use source water from Lake Taupo or the Waikato River. The remaining 21 distribution zones are predominantly supplied by groundwater. Issues for Pacific Health, Rotorua are as follows: • The consistent detection of arsenic in all distribution zones that have been assessed suggests that arsenic is

likely to be detected in unassessed drinking-water supplies; • The high number of distribution zones with arsenic identified at greater than 50% MAV (82%) suggest that

arsenic is likely to be detected at greater than 50% MAV in unassessed drinking-water supplies (especially those without effective removal of arsenic by treatment);

• There is a strong relationship between use of water from Lake Taupo or the Waikato River and the identification of arsenic at greater than 50% MAV;

• There is a strong relationship between the use of groundwater and detection of arsenic at greater than 50% MAV.

4.11.4.4 Pacific Health Whakatane Arsenic has been detected in 14 of the 21 distribution zones that have been assessed in the Pacific Health, Whakatane area. Of these, the concentration of arsenic was greater than 50% MAV in 6 of the zones. These serve a total population of 12,400. The 6 distribution zones belong within two communities, and are served by two sets of treatment plants. All 6 distribution zones are supplied by groundwater sources.


4.11.4.5 Pacific Health, Tauranga Arsenic has been detected in 6 of the 24 distribution zones that have been assessed in the Pacific Health, Tauranga area. Of these, the concentration of arsenic was greater than 50% MAV in 1 of the 24 zones. This zone serves a total population of 10. Arsenic appears to be less of an issue in this area. 4.11.5 Other distribution zones of importance due to population size 62 (89%) of the 70 distribution zones in which arsenic has been identified at greater than 50% MAV, are located within the Pacific Health (Rotorua, Whakatane and Tauranga) and Health Waikato areas. These serve a population of 226,686, which is 80% of the total population with arsenic at this level. Five of the remaining eight zones located in other areas are notable because of the size of the population they serve (greater than 500). These are shown in Table 4.5. These distribution zones are all served by groundwater sources.

Table 4.5 Drinking-water distribution zones located outside the Central Plateau/Waikato River area in which arsenic has been identified at greater than 50% MAV

Distribution zone code Distribution zone name Public Health Service Provider Population

WAI008VI Victoria Ave Auckland Healthcare 6700

WAI008CO Colombo Road Auckland Healthcare 550

NAP001NA Napier City Health Care Hawkes Bay 25800

NAP001TA Taradale Health Care Hawkes Bay 22100

FOX002FO Foxton MidCentral Health - Palm. Nth. 2700

4.11.6 Relationship between groundwater and arsenic The results presented in this report suggest that there is a positive relationship between use of groundwater sources and identification of arsenic at greater than 50% MAV. Results to demonstrate this relationship are presented in Table 4.6. Table 4.6 The relationship between various source types and the identification of arsenic in drinking-

water distribution zones at greater than 50% MAV

Source type Number of distribution zones

Percentage of total results greater than 50% MAV

Percentage of results, excluding those from zones using water from Lake

Taupo or Waikato River

Waikato River 19 27% /

Lake Taupo 12 17% /

Groundwater source 35 50% 90%

Other surface water 3 4% 10%

Rain water 1 1.5% 2.5%

It is possible that other elements, such as iron are associated with arsenic in groundwater. This has not been investigated. 4.11.7 Variability of the data The range of all arsenic concentrations is wide, with the maximum concentration 100 times higher than the limit of detection. The median concentration of all arsenic results is below the limit of detection due to the large number of results that were below this level. The wide range of results may arise from geographical or temporal variability. A study of temporal variability of results will only be possible once a suitable time series is available through collection of compliance monitoring data. 4.11.8 Supporting information Summarized results for arsenic are presented for each Public Health Unit in Appendix 1.2.



4.12 Barium 4.12.1 Summary information


50% MAV 0.35 mg/L


Assessed in the P2 Programme? Yes: All B. M1 and M2 by selection

Limit of detection for samples taken as part of the P2 Programme 0.01 mg/L (1.4% of MAV)


Number of community drinking-water zones with barium identified at > 50% MAV 4

Population served by community drinking-water zones with barium identified at greater than 50% MAV

287

Population served by community drinking-water zones with barium identified at greater than MAV, i.e. health significant concentrations

30 (1 zone)


Median of P2 Programme results 0.008 mg/L

Do the data suggest that barium is found more frequently in surface, ground or rain water

No

Do the data suggest that barium is found more frequently in large, small or school supplies

No

4.12.2 Detections up to 50% MAV Barium was detected in 592 zones (70% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for barium. 4.12.3 Supporting information Summarized results for barium are presented for each Public Health Unit in Appendix 1.3.

Number of detections to 50% of MAV

0

200

400

600

800

0-10% -20% -30% -40% -50%

per cent of MAV



4.13 Beryllium 4.13.1 Summary information Maximum Acceptable Value (MAV) 0.004 mg/L

50% MAV 0.002 mg/L

Remarks (from DWSNZ:2000) PMAV

Assessed in the P2 Programme? Yes: All B, by selection in M1 and M2



Number of community drinking-water zones with beryllium identified at > 50% MAV 0

Population served by community drinking-water zones with beryllium identified at greater than 50% MAV

0

Population served by community drinking-water zones with beryllium identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that beryllium is found more frequently in surface, ground or rain water

No

Do the data suggest that beryllium is found more frequently in large, small or school supplies

No

4.13.2 Detections up to 50% MAV Beryllium was detected in 62 zones (7% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for beryllium. 4.13.3 Unassessed zones The results suggest that it is presently unlikely for beryllium to be detected in New Zealand’s community drinking water supplies at >50% MAV. Where beryllium is detected, it is likely to be at a low percentage of its MAV. 4.13.4 Supporting information Summarized results for beryllium are presented for each Public Health Unit in Appendix 1.4.


0

20

40

60

80

0-10% -20% -30% -40% -50%

per cent of MAV


4.14 Boron

4.14.1 Summary information


50% MAV 0.7 mg/L






Number of community drinking-water zones with boron identified at > 50% MAV 8

Population served by community drinking-water zones with boron identified at greater than 50% MAV

3,372

Population served by community drinking-water zones with boron identified at greater than MAV, i.e. health significant concentrations

1,225 (3 zones)

Range of P2 Programme results nd – 11 mg/L


Do the data suggest that boron is found more frequently in surface, ground or rain water No

Do the data suggest that boron is found more frequently in large, small or school supplies

No

4.14.2 Detections up to 50% MAV Boron was detected in 129 zones (15% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for boron. 4.14.3 Supporting information Summarized results for boron are presented for each Public Health Unit in Appendix 1.5. 4.14.4 GIS plot The GIS plot indicates that boron detections that exceed or transgress the MAV are more likely in the North Island of New Zealand.

Number of detections to 50% of MAV

0

20

4060

80

100

0-10% -20% -30% -40% -50%

per cent of MAV



4.15 Cadmium 4.15.1 Summary information Maximum Acceptable Value (MAV) 0.003 mg/L

50% MAV 0.0015 mg/L





Number of community drinking-water zones with cadmium identified at > 50% MAV 54

Population served by community drinking-water zones with cadmium identified at greater than 50% MAV

140,609

Population served by community drinking-water zones with cadmium identified at greater than MAV, i.e. health significant concentrations

64,750 (30 zones)



Do the data suggest that cadmium is found more frequently in surface, ground or rain water

No

Do the data suggest that cadmium is found more frequently in large, small or school supplies

No

4.15.2 Detections up to 50% MAV Cadmium was detected in 188 zones (22% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for cadmium. 4.15.3 Supporting information Summarized results for cadmium are presented for each Public Health Unit in Appendix 1.6.


0102030405060

0-10% -20% -30% -40% -50%

per cent of MAV



4.16 Chlorine (free) 4.16.1 Summary information Maximum Acceptable Value (MAV) 5 mg/L

50% MAV 2.5 mg/L

Remarks (from DWSNZ:2000) ATO, disinfection must never be compromised

Assessed in the P2 Programme? No – has to be measured in the field


Number of community drinking-water zones with chlorine (free) identified at > 50% MAV

0

Population served by community drinking-water zones with chlorine (free) identified at greater than 50% MAV

0

Population served by community drinking-water zones with chlorine (free) identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that chlorine (free) is found more frequently in surface, ground or rain water

N/A

Do the data suggest that chlorine (free) is found more frequently in large, small or school supplies

N/A

Comment Chlorine has not been assessed in Phase 1 of the P2 Programme.


4.17 Chromium 4.17.1 Summary information Maximum Acceptable Value (MAV) 0.05 mg/L

50% MAV 0.025 mg/L

Remarks (from DWSNZ:2000) PMAV, limited information on health effects




Number of community drinking-water zones with chromium identified at > 50% MAV 1

Population served by community drinking-water zones with chromium identified at greater than 50% MAV

150

Population served by community drinking-water zones with chromium identified at greater than MAV, i.e. health significant concentrations

150 (1 zone)



Do the data suggest that chromium is found more frequently in surface, ground or rain water

No

Do the data suggest that chromium is found more frequently in large, small or school supplies

No

4.17.2 Detections up to 50% MAV Chromium was detected in 80 zones (9% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for chromium. 4.17.3 Supporting information Summarized results for chromium are presented for each Public Health Unit in Appendix 1.7.


0

20

40

60

80

0-10% -20% -30% -40% -50%

per cent MAV



4.18 Copper 4.18.1 Summary information Maximum Acceptable Value (MAV) 2 mg/L

50% MAV 1 mg/L

Remarks (from DWSNZ:2000) ATO




Number of community drinking-water zones with copper identified at > 50% MAV 68

Population served by community drinking-water zones with copper identified at greater than 50% MAV

55,319

Population served by community drinking-water zones with copper identified at greater than MAV, i.e. health significant concentrations

13,405 (24 zones)

Range of P2 Programme results nd – 10 mg/L


Do the data suggest that copper is found more frequently in surface, ground or rain water Possibly groundwater (see Appendix 1.8)

Do the data suggest that copper is found more frequently in large, small or school supplies

Found more frequently in school supplies – (20% of schools, 6% of zones >500, 5.5% of

zones <500) (see Appendix 1.8) 4.18.2 Detections up to 50% MAV Copper was detected in 832 zones (97% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for copper. 4.18.3 Supporting information Summarized results for copper are presented for each Public Health Unit in Appendix 1.8.


0

200

400

600

800

0-10% -20% -30% -40% -50%

per cent MAV



4.19 Cyanide (total) 4.19.1 Summary information Maximum Acceptable Value (MAV) 0.08 mg/L

50% MAV 0.04 mg/L


Assessed in the P2 Programme? Yes: In B for all unchlorinated zones, M1 and

M2 by selection

Limit of detection for samples taken as part of the P2 Programme 0.01 mg/L (12.5 % of MAV)

Number of community drinking-water zones with cyanide (total) identified at > 50% MAV

0

Population served by community drinking-water zones with cyanide (total) identified at greater than 50% MAV

0

Population served by community drinking-water zones with cyanide (total) identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that cyanide (total) is found more frequently in surface, ground or rain water

No

Do the data suggest that cyanide (total) is found more frequently in large, small or school supplies

No

4.19.2 Detections up to 50% MAV Cyanide has been detected in one zone, at 0.01 mg/L. Cyanide is considered to be effectively broken down (by oxidation) by chlorination of a supply. 4.19.3 Supporting information Summarized results for cyanide are presented for each Public Health Unit in Appendix 1.9.


4.20 Fluoride 2a 4.20.1 Summary information Maximum Acceptable Value (MAV) 1.5 mg/L

50% MAV 0.75 mg/L

Remarks (from DWSNZ:2000) The fluoride content recommended for drinking-water by the Ministry of Health for oral health reasons is 0.7 – 1.0 mg/L

Assessed in the P2 Programme? No: Fluoride automatically becomes classified

as P2 in all zones receiving fluoridated water


Number of community drinking-water zones with fluoride 2a identified at > 50% MAV 120

Population served by community drinking-water zones with fluoride 2a identified at greater than 50% MAV

1,893,344

Population served by community drinking-water zones with fluoride 2a identified at greater than MAV, i.e. health significant concentrations

N/A



Do the data suggest that cyanide (total) is found more frequently in surface, ground or rain water

N/A

Do the data suggest that cyanide (total) is found more frequently in large, small or school supplies

N/A

4.20.2 Supporting information Summarized data for fluoride 2a are presented for each Public Health Unit in Appendix 1.10.


4.21 Fluoride 2b 4.21.1 Summary information Maximum Acceptable Value (MAV) 1.5 mg/L

50% MAV 0.75 mg/L






Number of community drinking-water zones with fluoride identified at > 50% MAV 3

Population served by community drinking-water zones with fluoride identified at greater than 50% MAV

1,465

Population served by community drinking-water zones with fluoride identified at greater than MAV, i.e. health significant concentrations

63 (1 zone)



Do the data suggest that fluoride is found more frequently in surface, ground or rain water

No

Do the data suggest that fluoride is found more frequently in large, small or school supplies

No

4.21.2 Detections up to 50% MAV Fluoride was detected in 44 zones (5% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for fluoride. 4.21.3 Supporting information Summarized results for fluoride 2b are presented for each Public Health Unit in Appendix 1.11.


0

5

10

15

20

0-10% -20% -30% -40% -50%

per cent of MAV



4.22 Lead 4.22.1 Summary information Maximum Acceptable Value (MAV) 0.01 mg/L

50% MAV 0.005 mg/L





Number of community drinking-water zones with lead identified at > 50% MAV 323

Population served by community drinking-water zones with lead identified at greater than 50% MAV

612,278

Population served by community drinking-water zones with lead identified at greater than MAV, i.e. health significant concentrations

477,314 (195 zones)



Do the data suggest that lead is found more frequently in surface, ground or rain water No

Do the data suggest that lead is found more frequently in large, small or school supplies No 4.22.2 Detections up to 50% MAV Lead was detected in 731 zones (85% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for lead. 4.22.3 Supporting information Of all the chemicals that have been assessed, lead is the individual determinand that has been identified in distribution zones at greater than 50% MAV the greatest number of times (323). The total population served by these distribution zones is high (approximately 600,000). Summarized results for lead are presented for each Public Health Unit in Appendix 1.12.


0

50

100

150

0-10% -20% -30% -40% -50%

per cent MAV



4.23 Lithium 4.23.1 Summary information Maximum Acceptable Value (MAV) 0.9 mg/L

50% MAV 0.45 mg/L




Number of community drinking-water zones with lithium identified at > 50% MAV 0

Population served by community drinking-water zones with lithium identified at greater than 50% MAV

0

Population served by community drinking-water zones with lithium identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that lithium is found more frequently in surface, ground or rain water

N/A

Do the data suggest that lithium is found more frequently in large, small or school supplies

N/A

Comment Lithium has not been assessed in Phase 1 of the P2 Programme, because it was introduced in the DWSNZ:2000.


4.24 Manganese 4.24.1 Summary information Maximum Acceptable Value (MAV) 0.5 mg/L

50% MAV 0.25 mg/L






Number of community drinking-water zones with manganese identified at > 50% MAV 23

Population served by community drinking-water zones with manganese identified at greater than 50% MAV

10,210

Population served by community drinking-water zones with manganese identified at greater than MAV, i.e. health significant concentrations

1,551 (6 zones)



Do the data suggest that manganese is found more frequently in surface, ground or rain water

Yes, groundwater 74% of results >50% MAV are from zones using groundwater only (see

Appendix 1.13)

Do the data suggest that manganese is found more frequently in large, small or school supplies

The ease with which manganese is removed by water treatment is likely to influence the lower

frequency of concentrations >50% MAV in larger supplies (see Appendix 1.13)

4.24.2 Detections up to 50% MAV Manganese was detected in 286 zones (33% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for manganese. The frequency distribution graph for manganese, shows that the majority of detections are between 0 and 10% of MAV. The limit of detection for manganese is 0.2% of its MAV. The low number of detections above 10% MAV, indicate that for manganese, most results are comfortably below 50% MAV, and it would take a large increase to push them over this concentration.


0

100

200

300

0-10% -20% -30% -40% -50%

per cent of MAV


4.24.3 Relationship between groundwater and manganese The results presented in this report suggest that there is a positive relationship between use of groundwater sources and identification of manganese at greater than 50% MAV. 74 % of distribution zones with manganese identified at greater than 50% MAV were supplied solely by groundwater. This increases to 87% if zones fed by groundwater plus another source type are included. The presence of manganese in distribution zones registered as using rain water is also of note, and may be caused by registration inaccuracies rather than manganese in rain water, in which case the link with groundwater may be even stronger. The relationship between groundwater and manganese is detailed in Appendix 1.17. 4.24.4 Variability of the data The range of manganese concentrations is wide, but generally not of concern. The maximum concentration (1.7 mg/L) is approximately 1000 times higher than the median, but still only 3.4 times the MAV. The median concentration of all manganese results is 0.002 mg/L, which is only 0.4% of the MAV. 4.24.5 Supporting information Summarized results for manganese are presented for each Public Health Unit in Appendix 1.13. Because the concentration of manganese can be reduced in water through simple oxidation processes, samples taken following treatment may not represent the concentration of manganese in raw water. Samples taken for the P2 Programme are taken following treatment and the results presented here are therefore limited to evaluating its public health significance in the supplies that have been assessed. Results obtained through the National Groundwater Monitoring Programme are likely to give a better representation of manganese concentrations in raw water. The National Groundwater Monitoring Programme (NGMP) is co-ordinated and managed by the Institute of Geological and Nuclear Sciences (GNS) under contract to the Foundation for Research, Science and Technology and the Ministry for the Environment’s Sustainable Management Fund, and with the co-operation of New Zealand’s regional councils (Rosen, 1999, Rosen 2001).



4.25 Mercury (total) 4.25.1 Summary information Maximum Acceptable Value (MAV) 0.002 mg/L

50% MAV 0.001 mg/L


Assessed in the P2 Programme? Yes: M1 and M2 by selection



Number of community drinking-water zones with mercury (total) identified at > 50% MAV

1

Population served by community drinking-water zones with mercury (total) identified at greater than 50% MAV

100

Population served by community drinking-water zones with mercury (total) identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that mercury (total) is found more frequently in surface, ground or rain water

No

Do the data suggest that mercury (total) is found more frequently in large, small or school supplies

No

4.25.2 Detections up to 50% MAV Mercury has been detected in three zones. 4.25.3 Supporting information Summarized results for mercury are presented for each Public Health Unit in Appendix 1.14.


4.26 Molybdenum

4.26.1 Summary information Maximum Acceptable Value (MAV) 0.07 mg/L

50% MAV 0.035 mg/L





Number of community drinking-water zones with molybdenum identified at > 50% MAV

0

Population served by community drinking-water zones with molybdenum identified at greater than 50% MAV

0

Population served by community drinking-water zones with molybdenum identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that molybdenum is found more frequently in surface, ground or rain water

No

Do the data suggest that molybdenum is found more frequently in large, small or school supplies

No

4.26.2 Detections up to 50% MAV Molybenum was detected in 35 zones (4% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for molybenum. 4.26.3 Supporting information Summarized results for molybdenum are presented for each Public Health Unit in Appendix 1.15.


0

10

20

30

40

0-10% -20% -30% -40% -50%

per cent of MAV



4.27 Nickel 4.27.1 Summary information Maximum Acceptable Value (MAV) 0.02 mg/L

50% MAV 0.01 mg/L





Number of community drinking-water zones with nickel identified at > 50% MAV 123

Population served by community drinking-water zones with nickel identified at greater than 50% MAV

364,216

Population served by community drinking-water zones with nickel identified at greater than MAV, i.e. health significant concentrations

286,742 (83 zones)



Do the data suggest that nickel is found more frequently in surface, ground or rain water No

Do the data suggest that nickel is found more frequently in large, small or school supplies

No

4.27.2 Detections up to 50% MAV Nickel was detected in 551 zones (64% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for nickel. 4.27.3 Supporting information Summarized results for nickel are presented for each Public Health Unit in Appendix 1.16.


0

50100

150200

250

0-10% -20% -30% -40% -50%

per cent MAV



4.28 Nitrate 4.28.1 Summary information Maximum Acceptable Value (MAV) 50 (11.29 as nitrate-N) mg/L

50% MAV 25 (5.65 as nitrate-N) mg/L

Remarks (from DWSNZ:2000) The sum of the ratio of the concentrations of nitrate and nitrite to each of their respective MAVs should not exceed 1


Limit of detection for samples taken as part of the P2 Programme 0.1 as nitrate-N mg/L (0.9% of MAV)


Number of community drinking-water zones with nitrate identified at > 50% MAV 50

Population served by community drinking-water zones with nitrate identified at greater than 50% MAV

102,264

Population served by community drinking-water zones with nitrate identified at greater than MAV, i.e. health significant concentrations

1,017 (6 zones)

Range of P2 Programme results nd – 30 mg/L as nitrate-N

Median of P2 Programme results 0.2 mg/L as nitrate-N

Do the data suggest that nitrate is found more frequently in surface, ground or rain water Yes. Groundwater, 86% of results >50% are for zones using groundwater only (see

Appendix 1.17)

Do the data suggest that nitrate is found more frequently in large, small or school supplies

Yes, schools,: 16% of schools have nitrate >50% MAV, 2% of zones with population

>500 and 6% of zones with population <500 (see Appendix 1.17)

4.28.2 Detections up to 50% MAV Nitrate was detected in 529 zones (62% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for nitrate. The frequency distribution graph for nitrate, shows a peak of detections between 0 and 10% of MAV. The limit of detection for nitrate is 0.9% of its MAV. There is a decline in the number of detections as 50% of MAV is reached, indicating that for nitrate, most results are comfortably below 50% MAV, and it would take a large increase to push them over this concentration. However, the number of detections between 30% and 50% MAV is quite sizeable, and the absence of time series data for distribution zones prohibits any interpretation of how important these results are.


0

100

200

300

400

0-10% -20% -30% -40% -50%

per cent of MAV


4.28.3 Relationship between groundwater and nitrate The results presented in this report suggest that there is a positive relationship between use of groundwater sources and identification of nitrate at greater than 50% MAV. 86% of distribution zones with nitrate identified at greater than 50% MAV were supplied by groundwater. Results are presented in Appendix 1.17. 4.28.4 Distribution zone type Nitrate has predominantly been identified in distribution zones that serve small populations. The results presented in this report also suggest that there is a positive relationship between school supplies and identification of nitrate at greater than 50% MAV. Twenty school supplies have had nitrate identified at greater than 50% MAV, and this represents 16% of all schools assessed and 40% of all distribution zones with nitrate at this level. As expected, groundwater is the dominant source type for schools with nitrate (16 of the 20 zones). The rural location of schools that are served by their own drinking-water supply may be an influential factor in the elevated levels of nitrate associated with many school supplies. 4.28.5 Variability of data The range of nitrate concentrations is wide, with the maximum concentration (30 mg/L) approximately 150 times higher than the limit of detection and 2.7 times higher than the MAV. The median concentration of all nitrate results is 0.2 mg/L, which is 1.8% of the MAV. The wide range of results may result from geographical or temporal variability of results. A study of temporal variability of results, allowing assessment of the importance of these nitrate results, will only be possible once a suitable time series is available. The potential for nitrate concentrations in drinking-water to rise, as a result of intensification of agriculture, is of note. 4.28.3 Supporting information Summarized results for nitrate are presented for each Public Health Unit in Appendix 1.17.



4.29 Nitrite 4.29.1 Summary information Maximum Acceptable Value (MAV) 3 (0.91 as nitrite-N) mg/L

50% MAV 1.5 (0.46 as nitrite-N) mg/L

Remarks (from DWSNZ:2000) The sum of the ratio of the concentrations of nitrate and nitrite to each of their respective MAVs should not exceed 1

Assessed in the P2 Programme? Yes: M1 and M2 by selection until 199? when

analysis was ceased

Limit of detection for samples taken as part of the P2 Programme 0.005 as nitrite-N mg/L (0.5% of MAV)


Number of community drinking-water zones with nitrite identified at > 50% MAV 0

Population served by community drinking-water zones with nitrite identified at greater than 50% MAV

0

Population served by community drinking-water zones with nitrite identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd – 0.088 mg/L as nitrite N


Do the data suggest that nitrite is found more frequently in surface, ground or rain water No

Do the data suggest that nitrite is found more frequently in large, small or school supplies

No

4.29.2 Detections up to 50% MAV There have been five detections of nitrite. Because all of the results for nitrite were well below 50% MAV, analysis was halted in December 1998. All zones investigated after this time have not been assessed for nitrite. 4.29.3 Supporting information Summarized results for nitrite are presented for each Public Health Unit in Appendix 1.18.


4.30 Selenium 4.30.1 Summary information Maximum Acceptable Value (MAV) 0.01 mg/L

50% MAV 0.005 mg/L





Number of community drinking-water zones with selenium identified at > 50% MAV 2

Population served by community drinking-water zones with selenium identified at greater than 50% MAV

502

Population served by community drinking-water zones with selenium identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that selenium is found more frequently in surface, ground or rain water

No

Do the data suggest that selenium is found more frequently in large, small or school supplies

No

4.30.2 Detections up to 50% MAV Selenium was detected in 35 zones (4% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for selenium. 4.30.3 Supporting information Summarized results for selenium are presented for each Public Health Unit in Appendix 1.19.

Detections to 50% MAV

0

5

10

15

20

0-10% -20% -30% -40% -50%

per cent of MAV



4.31 Silver 4.31.1 Summary information Maximum Acceptable Value (MAV) 0.02 mg/L

50% MAV 0.01 mg/L

Remarks (from DWSNZ:2000) U PMAV Australian provisional value




Number of community drinking-water zones with silver identified at > 50% MAV 0

Population served by community drinking-water zones with silver identified at greater than 50% MAV

0

Population served by community drinking-water zones with silver identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that silver is found more frequently in surface, ground or rain water No

Do the data suggest that silver is found more frequently in large, small or school supplies

No

4.31.2 Detections up to 50% MAV Silver has been detected in 14 community drinking-water supplies. 4.31.3 Supporting information Summarized results for silver are presented for each Public Health Unit in Appendix 1.20.


4.32 Tin 4.32.1 Summary information Maximum Acceptable Value (MAV) 1 mg/L

50% MAV 0.5 mg/L

Remarks (from DWSNZ:2000) U PMAV derived from WHO data




Number of community drinking-water zones with tin identified at > 50% MAV 0

Population served by community drinking-water zones with tin identified at greater than 50% MAV

0

Population served by community drinking-water zones with tin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that tin is found more frequently in surface, ground or rain water No

Do the data suggest that tin is found more frequently in large, small or school supplies No 4.32.2 Detections up to 50% MAV Tin was detected in 60 zones (7% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for tin. 4.32.3 Supporting information Summarized results for tin are presented for each Public Health Unit in Appendix 1.21.


0

20

40

60

80

0-10% -20% -30% -40% -50%

per cent MAV



4.33 Uranium 4.33.1 Summary information Maximum Acceptable Value (MAV) 0.002 mg/L

50% MAV 0.001 mg/L

Remarks (from DWSNZ:2000) PMAV: WHO provisional




Number of community drinking-water zones with uranium identified at > 50% MAV 0

Population served by community drinking-water zones with uranium identified at greater than 50% MAV

0

Population served by community drinking-water zones with uranium identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd


Do the data suggest that uranium is found more frequently in surface, ground or rain water

N/A

Do the data suggest that uranium is found more frequently in large, small or school supplies

N/A

4.33.2 Detections up to 50% MAV There have been no detections of uranium. 4.33.3 Unassessed zones The results suggest that it is presently unlikely for uranium to be detected in New Zealand’s community drinking-water supplies.


CHAPTER 5: DISINFECTION BY-PRODUCTS (DBPs) 5.1 Introduction This chapter reports on detections of disinfection by-products in New Zealand’s community drinking-water supplies. Disinfection by-products are compounds that form as a direct result of the intentional addition of a disinfectant to drinking-water in order to improve its microbiological safety. All disinfectants, except ultraviolet irradiation (research on this is yet to be done) offer the potential for undesirable disinfection by-products to be produced (MoH, 1995b). The Ministry of Health has a clear message with regard to disinfection-by-product formation, and this is that the microbiological quality of the water must not be sacrificed to minimise disinfection by-product formation. (MoH 1995b, MoH 2000a). Nineteen disinfection by-products, or disinfection by-product families are allocated Maximum Acceptable Values (MAVs) or provisional Maximum Acceptable Values (PMAVs) in Tables 14.2 and 14.3 of the Drinking-Water Standards for New Zealand:2000 (DWSNZ:2000) (MoH 2000a). Seventeen have been assessed and are considered in this chapter. The two disinfection by-products that have not been assessed are chlorite and monochloramine. Chlorite is a disinfection by-product associated with the use of chlorine dioxide as a disinfectant. None of the drinking-water supplies that have been assessed used chlorine dioxide as a disinfectant, and so it has not been looked for. Monochloramine needs to be measured in the field for accurate results to be obtained. Monochloramine has consequently not been assessed. Analysis for cyanogen chloride was discontinued from the 1996/97 P2 Programme Round onwards when it became clear that laboratory measurements for this disinfection by-product were not yielding satisfactory results. Examination of literature available concerning the stability of cyanogen chloride under water treatment conditions indicate that analysis is required within a few hours of sampling, even with sample dechlorination, if there is to be any chance of detecting the compound. Trihalomethanes and haloacetic acids are both disinfection by-product families and their MAV is based upon the sum of the ratios of the concentration of each member to its respective MAV (see section 4.2 for more information on DBP families). Thus the assessment for these two determinands is based on calculation of a ratio derived from the analytical results for members of their chemical family, rather than any direct assessment. Analysis for disinfection by-products that belong within the haloacetonitrile family (HANs) was halted in the 1996/97 Round of the P2 Programme in an effort to save Programme resources. All results obtained had confirmed that, where detected, the concentrations of all HANs were an order of magnitude below their MAVs. Haloacetonitriles are considered to have been adequately assessed.


5.2 DBP families/groups Several of the disinfection by-products assessed in this chapter are members of chemical families that have similar properties. The families of note are summarised in Table 5.1.

Table 5.1 Disinfection by-product chemical families Disinfection by-product name MAV

mg/L Inorganic or organic

Family or class (by functional group)

Bromodichloromethane 0.06 Organic Trihalomethane (THM) Bromoform 0.1 Organic Trihalomethane (THM) Chloroform 0.2 Organic Trihalomethane (THM) Dibromoacetonitrile 0.2 Organic Haloacetonitrile (HAN) Dibromochloromethane 0.1 Organic Trihalomethane (THM) Dichloroacetic acid 0.05 Organic Haloacetic acid (HAA) Dichloroacetonitrile 0.1 Organic Haloacetonitrile (HAN) Trichloroacetic acid 0.1 Organic Haloacetic acid (HAA) Trihalomethanes Ratio = 1 Organic Trihalomethane family (THMs) Haloacetic acids Ratio = 1 Organic Haloacetic acid family (HAAs) Bromochloroacetic acid No MAV Organic Haloacetic acid (HAA) Dibromoacetic acid No MAV Organic Haloacetic acid (HAA) Monochloroacetic acid No MAV Organic Haloacetic acid (HAA) Bromochloroacetonitrile No MAV Organic Haloacetonitrile (HAN) Bromochloromethane No MAV Organic Trihalomethane (THM)

In situations where more than one determinand acts together in terms of health significance, the Drinking-Water Standards for New Zealand:2000 provide MAVs for the combined concentrations of these determinands. This is the case for the trihalomethanes (THMs) and haloacetic acids (HAAs). For these DBPs, their combined health significance is determined through addition of all the ratios of the individual DBPs in a family to their MAVs. The mathematical expressions are as follows: Trihalomethanes (THMs) [Chloroform]MAV

[Bromodichloromethane]MAV

[Dibromochloromethane]MAV

[Bromoform]MAVchloroform bromodichloromethane dibromochloromethane bromoform

+ + + ≤1 Haloacetic Acids (HAAs) [Dichloroacetic Acid]

MAV

[Trichloroacetic Acid]MAVdichloroacetic acid trichloroacetic acid

+ ≤1

The square brackets are a shorthand notation to mean “concentration”, thus [Chloroform] means “the chloroform concentration”. To evaluate these equations the concentration of each DBP is divided by its MAV, then all of these results are added together to obtain a total value. If this value is greater than 1, the sample transgresses the MAV. Recommendations for P2 classification of trihalomethane or haloacetic acid families are made when the above calculations yield values greater than 0.5.


Phase 1 of the P2 Programme covered the period 1995 – 2000. During this time, the version of drinking water standards in use was the Drinking-Water Standards for New Zealand:1995 (DWSNZ:1995) (MoH 1995). The following changes are seen in the DWSNZ:2000: MAVs for inorganic determinands that were previously listed, but without MAVs: Chlorate

Altered MAVs: None

Chlorate arises in chlorinated supplies as a result of the decomposition of hypochlorite in high concentration chlorine solutions. Chlorate has been assessed in all zones that use sodium or calcium hypochlorite as a method of disinfection. The results from these assessments have been compared against the new MAV in this report. Emerging issue: Chlorate has been identified at greater than 50% of its MAV in distribution zones serving high populations. The health significance of the chlorate results presented in this chapter have not been previously reported (because there was no MAV). 5.3 Origins of the analytical data 5.3.3 P2 Programme: Baseline sampling The first set of sampling undertaken in a P2 Programme assessment is termed the ‘Baseline’ sampling round. Disinfection by-products are not included in the Baseline sampling round. 5.3.4 P2 Programme: M1 and M2 sampling The first and second monitoring rounds (M1 and M2), which follow the Baseline sampling round for each zone are targeted towards those determinands that have been identified as having the potential to be present in the zone at health significant concentrations. In the case of disinfection by-products, samples were collected for analysis for all disinfection by-products for all distribution zones receiving disinfected water. The selection of disinfection by-products was based upon the disinfection method employed at the treatment plant/booster pumps. Disinfection by-product formation results from a number of factors. The ability with which treatment plant processes remove the disinfection by-product precursors contained within the source water, the dosage of disinfectant, the stage at which the disinfectant is introduced, and the length of time that the water is in contact with it are all important to the final formation of disinfection by-products. For the purpose of assessment of the chemical quality of water reaching the consumer, it was requested that samples for disinfection by-product formation were taken as follows: 1. After a significant rainfall event; 2. On confirmation of adequate disinfection; 3. From a location at the extremities of the distribution system, in order to gain samples that

had received maximal contact time with the disinfectant.


5.4 Summary of results Table 5.2 presents a summary of results collected for each disinfection by-product covered in this chapter. Further details relating to each determinand can be found by referring to the page dedicated to it. Table 5.2 Summary table for disinfection by-products = Yes = No Disinfection by-product MAV

mg/L Assessed Detected > 50% MAV Transgression

Bromate 0.025 Chlorate 0.3 64 zones 32 zones 8 zones Bromodichloromethane THM 0.06 375 zones 4 zones Bromoform THM 0.1 96 zones Chlorite 0.3 Chloroform THM 0.2 374 zones 2 zones Cyanogen chloride (as CN) 0.08 until 96/97*

Dibromoacetonitrile 0.2 7 zones Dibromochloromethane THM 0.1 258 zones Dichloroacetic acid HAA 0.05 203 zones 38 zones 5 zones Dichloroacetonitrile 0.1 29 zones Dichloromethane 0.02 Formaldehyde 1 Monochloramine 3 Trichloroacetaldehyde/chloral hydrate

0.01 195 zones 75 zones 17 zones

Trichloroacetic acid HAA 0.1 209 zones 23 zones 1 zone Trichloroacetonitrile 0.001 Trihalomethanes (THMs) 34 zones 2 zones Haloacetic acids (HAAs) 71 zones 28 zones Bromochloroacetic acid No MAV 51 zones No MAV No MAV

Dibromoacetic acid No MAV 12 zones No MAV No MAV

Monochloroacetic acid No MAV 3 zones No MAV No MAV

Bromochloroacetonitrile No MAV 1 zone No MAV No MAV

Bromochloromethane No MAV 12 zones No MAV No MAV

Dibromomethane No MAV 6 zones No MAV No MAV

1,1-Dichloropropan-2-one No MAV 4 zones No MAV No MAV

1,1,1-Trichloropropan-2-one No MAV 50 zones No MAV No MAV

*Analysis for cyanogen chloride was discontinued from the 1996/97 Programme Round onwards. 5.5 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) Nineteen disinfection by-products have been assessed. Transgressions of the MAVs were identified in one or more zones for six deteminands. Concentrations that exceeded 50% of the


MAVs were identified in one or more zones for eight determinands. A summary is provided in Table 5.3. Table 5.3 Disinfection by-products detected at greater than 50% MAV or transgressing

their MAV Determinand Identified at greater than 50% MAV Identified at greater than MAV

Number of zones Population Number of zones Population

Bromodichloromethane THM 4 8,080 0 0 Chlorate 32 423,526 8 1,505 Chloroform THM 2 540 0 0 Dichloroacetic acid HAA 38 68,123 5 3,160 Trichloroacetaldehyde/chloral hydrate 75 233,249 17 46,975 Trichloroacetic acid HAA 23 41,100 1 240 Trihalomethanes (THMs) 34 76,123 2 4,900 Haloacetic acids (HAAs) 71 161,980 28 55,814

The percentages of large (greater than 500 population) and small (500 or fewer population) non-school supplies disinfection by-products identified at greater than 50% MAV is virtually the same. There is no apparent link between the size of non-school supplies and the percentage in which disinfection by-products have been identified at greater than 50% MAV. Disinfection by-products are not a significant issue in schools because few schools disinfect their water on a continual basis. 5.6 Detections to 50% MAV Of the nineteen disinfection by-products that have been assessed, four were not detected in any zones. These are shown in Table 5.4. Table 5.4 Disinfection by-products that have not been detected in any distribution

zones

Disinfection by-product Comment

Bromate

Formaldehyde

These are disinfection by-products associated with use of ozonation for disinfection. Ozonation is not a common choice of disinfectant and hence the number of zones for which samples have been taken for bromate and formaldehyde analysis is low

Dichloromethane Limit of detection = 40% MAV (see Table 5.5)

Trichloroacetonitrile Analysis for haloacetonitiles (HANs) was discontinued in the 1996/97 Round of the P2 Programme because, when detected, their concentrations were all sufficiently below their MAVs

Eleven individual disinfection by-products were detected in one or more zones. The combined health significance of trihalomethanes and haloacetic acids has been determined through addition of all the ratios of the individual DBPs in a family to their MAVs. These two disinfection by-product families have both been detected in a number of zones, making a total of thirteen disinfection by-products that have been detected. Limits of detection, and distribution patterns for concentrations detected were examined, and comments are presented in Table 5.5. Disinfection by-products for which the limits of detection are above 20% MAV are shaded.


Table 5.5 Range & medians for all disinfection by-products detections, plus analytical limits of detection

Disinfection by-product Limit of

detection mg/L

Limit of detection as a % of the MAV

Minimum mg/L

Median mg/L

Maximum mg/L

Comment

Bromate 0.008 32 nd nd nd Chlorate 0.05 16.7 nd nd 2.2 Bromodichloromethane THM 0.002 3.3 nd 0.0031 0.055 Bromoform THM 0.001 1 nd nd 0.049 Most detections are

between 0 and 10% MAV

Chlorite Not assessed

Not assessed Not assessed

Not assessed

Not assessed

Chloroform THM 0.004 2 nd 0.0068 0.141 Most detections are between 0 and 10% MAV. The two results >50% MAV are approximately 15 fold higher than the median

Cyanogen chloride (as CN)* nd nd nd Dibromoacetonitrile 0.002 1 nd nd 0.0041 Dibromochloromethane THM 0.002 2 nd nd 0.028 Dichloroacetic acid HAA 0.005 10 nd nd 0.072 Dichloroacetonitrile 0.002 2 nd nd 0.0079 Most detections are

between 0 and 10% MAV

Dichloromethane 0.008 40 nd nd nd Formaldehyde 0.01 1 nd nd nd Monochloramine Not

assessed Not assessed Not

assessed Not assessed

Not assessed

Trichloroacetaldehyde/chloral hydrate

0.002 20 nd nd 0.030

Trichloroacetic acid HAA 0.005 5 nd nd 0.115 Trichloroacetonitrile 0.0002 20 nd nd nd Trihalomethanes (THMs) Calc. Calc. Calc. Calc. Calc. Haloacetic acids (HAAs) Calc. Calc. Calc. Calc. Calc. * Analysis discontinued from the 1996/97 Programme Round onwards The methods used for analysis of disinfection by-product groups provide results that include several other disinfection by-products, for which no MAVs have been set. Detections were recorded for the following chemicals: monochloroacetic acid, bromochloroacetonitrile, dibromomethane, 1,1-dichloropropan-2-one and 1,1,1-trichloropropan-2-one. It is not possible to comment on the health significance of these detections, because no MAVs have been set.


Figure 5.1 Populations served by distribution zones in which disinfection by-products have been identified at greater than 50% Maximum Acceptable Value

5.7 Geographical distribution Examination of the GIS plots showing the geographical distribution of the Total Trihalomethanes, Total Haloacetic Acids, and chloral hydrate shows that organic disinfection by-products are detected more frequently and at higher concentrations in the some parts of the country than others. Areas where disinfection by-product formation is most marked are:

• South east Otago • Wellington and Manawatu • Taranaki • Central North Island and through the Waikato up to Auckland. • Western Bay of Plenty

Disinfection by-product concentrations are seldom elevated in Canterbury and Hawkes Bay. These geographical distributions are likely to reflect the nature of the source waters in these areas and the concentrations of natural organic matter they contain. Links between source type and disinfection by-product formation are discussed below. Chlorate was detected in several supplies in North Otago and South Canterbury, but the greatest number of zones with elevated concentrations of chlorate appear in the northern part of the North Island. The geographical distribution of this disinfection by-product is unlike those of the others, because it is not formed through the reaction of chlorine with organic matter; it forms as the chlorine decomposes when stored in solution. Supplies in which it was detected are chlorinated with calcium or sodium hypochlorite, although not all supplies using these forms of chlorine contained detectable chlorate concentrations. The reasons for its appearance in some supplies are not presently understood.


5.8 Source types Clear correlations between the type of source used for a supply and both the concentrations of natural organic matter in the water and the concentrations of disinfection by-products formed have been found in New Zealand waters (Nokes 1999b). Total organic carbon concentrations, which are a measure of the natural organic matter content of the water, are generally higher in surface waters than groundwaters. Disinfection by-products are formed from natural organic matter, and consequently their formation is also usually greater in surface waters. Disinfection by-product formation also tends to be greater when the source is a river or stream than when it is a lake or reservoir. This is probably because the water in lakes and reservoirs is less prone to periods of poor quality during high rainfall when the concentration of natural organic matter in the water is high. Groundwaters are the predominant source waters in Canterbury and Hawkes Bay, and this is likely to be an important factor contributing to the geographical distribution noted in the previous section. The groundwaters used as the sources for may small communities in these regions may not be chlorinated, which will also be a factor leading to the small number of zones in which disinfection by-product formation is important. 5.9 Unassessed zones The total organic carbon (TOC) concentration, or the ultraviolet absorbance of the water at 254 nm (A254), are both measurements of the organic content of the water. They therefore provide an indication of the extent to which disinfection by-products may form when the water is chlorinated. These determinands therefore offer a means of estimating the likely importance of disinfection by-product formation in unassessed zones that does not require expensive analysis for trace organics. Statistical analysis of relationships between various disinfection by-products and these two measures of organic matter show that disinfection by-product formation is unlikely to be a health concern in waters with a TOC less than or equal to 1 mg of C/L, or an A254 value less than or equal to 0.03AU (Nokes 1999b). It is highly likely that disinfection by-product formation will be potentially health-significant when the TOC concentration exceeds 2 mg of C/L and the A254 value exceeds 0.06AU. Where TOC and A254 values are unavailable, some guide to the likelihood of disinfection by-product formation can be gained from consideration of the type of source being used (Nokes 1999b). 5.10 Gaps in the information 5.10.1 Disinfection using ozonation The Priority 2 Programme has only assessed drinking-water supplies that serve populations greater than 100. The formation of bromate and formaldehyde has not been well assessed through the P2 Programme because of the lack of drinking-water supplies that serve populations greater than 100 and that use ozonation as a method of disinfection.


5.10.2 Limitations of laboratory measurements Monochloramine has not been assessed because it needs to be assessed in the field. Cyanogen chloride assessments were halted in the 1996/97 P2 Programme Round because examination of literature available concerning the stability of cyanogen chloride under water treatment conditions indicated that analysis was required within a few hours of sampling, even with sample dechlorination, if there was to be any chance of detecting the compound. 5.10.3 Disinfection using chlorine dioxide Chlorite has not been assessed because of the lack of drinking-water supplies that serve populations greater than 100 and that use chlorine dioxide as a method of disinfection. 5.10.4 Inadequate limits of detection The detection limits for bromate and dichloromethane exceeded 20% MAV and as such are not considered to have been assessed as appropriately as other determinands. 5.10.5 Absence of MAVs The absence of MAVs for monochloroacetic acid and bromochloroacetonitrile is of note because they have been detected in New Zealand’s community drinking-water supplies and health concerns have been raised about them (Table 14.7 of the DWSNZ:2000, MoH 2000a). These determinands do not have MAVs set because there is inadequate data to permit this. In the case of monochloroacetic acid, there may be a contribution to the haloacetic acid family, as well as a health significant effect for all detections recorded. The absence of MAVs for these disinfection by-products prohibits any interpretation of the significance of the detections. Six other disinfection by-products have been detected in addition to the two mentioned above, and there is an absence of New Zealand health related information relating to these determinands. These determinands are: Bromochloroacetic acid, dibromoacetic acid, bromochloroacetonitrile, bromochloromethane, dibromomethane, 1,1-dichloropropan-2-one and 1,1,1-trichloropropan-2-one.


5.11 Bromate 5.11.1 Summary information Synonyms None


50% MAV 0.0125 mg/L

Remarks (from DWSNZ:2000) For excess lifetime cancer risk of 7 x 10 -5

Assessed in the P2 Programme? Yes: M1 and M2 for all ozonated zones

Limit of detection for samples taken as part of the P2 Programme 0.008 mg/L (32 % of MAV)

Total number of samples analysed for this determinand in Phase 1 of the P2 Programme

6 samples

Number of community drinking-water zones with bromate identified at > 50% MAV

0

Population served by community drinking-water zones with bromate identified at greater than 50% MAV

0

Population served by community drinking-water zones with bromate identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd – nd


Do the data suggest that bromate is found more frequently in surface, ground or rain water

Disinfection by-products are not present in source waters. They form in a complex series of reactions

between the disinfectant added at the treatment plant, and precursors contained within the source water. They are only an issue for those supplies

that are disinfected.

Do the data suggest that bromate is found more frequently in large, small or school supplies

No

5.11.2 Detections up to 50% MAV There have been no detections of bromate. Bromate is a disinfection by-product associated with disinfection by ozonation. Samples have been analysed in zones that rececive water disinfected by ozonation (6 zones). 5.11.3 Supporting information Summarized results for bromate are presented for each Public Health Unit in Appendix 2.1.


5.12 Bromodichloromethane THM 5.12.1 Summary information Synonyms Dichlorobromomethane


50% MAV 0.03 mg/L

Remarks (from DWSNZ:2000) for excess lifetime cancer risk of 10 -5

Assessed in the P2 Programme? Yes: M1 and M2 for all disinfected (chlorinated)

zones

Limit of detection for samples taken as part of the P2 Programme 0. 002 mg/L (3.3% % of MAV)


511 samples

Number of community drinking-water zones with bromodichloromethane identified at > 50% MAV

4

Population served by community drinking-water zones with bromodichloromethane identified at greater than 50% MAV

8,080

Population served by community drinking-water zones with bromodichloromethane THM identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that bromodichloromethane is found more frequently in surface, ground or rain water




Do the data suggest that bromodichloromethane is found more frequently in large, small or school supplies

No

5.12.2 Detections up to 50% MAV Bromodichloromethane was detected in 375 zones (44% of those assessed, 73% of those disinfected). Detections are expressed in terms of their percentage of the MAV for bromodichloromethane. Bromodichloromethane is a member of the trihalomethane (THM) ‘family’, and as such is included in the determinand ‘THM’ which is included later in this chapter. 5.12.3 Supporting information Summarized results for bromodichloromethane are presented for each Public Health Unit in Appendix 2.2.



5.13 Bromoform THM


Synonyms Tribromomethane


50% MAV 0.05 mg/L

Remarks (from DWSNZ:2000)

Assessed in the P2 Programme? Yes: M1 and M2 for all disinfected (chlorinated

and ozonated) zones


Number of community drinking-water zones with bromoform identified at > 50% MAV

0

Population served by community drinking-water zones with bromoform identified at greater than 50% MAV

0

Population served by community drinking-water zones with bromoform identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that bromoform is found more frequently in surface, ground or rain water




Do the data suggest that bromoform is found more frequently in large, small or school supplies

No

5.13.2 Detections up to 50% MAV

Bromoform was detected in 96 zones (11% of those assessed, 19% of those disinfected). A representation of the frequency with which detections to 50% were found in shown in the bar chart below.

Detections are expressed in terms of their percentage of the MAV for bromoform. Bromoform is a member of the trihalomethane (THM) ‘family’, and as such is included in the determinand ‘THM’ which is included later in this chapter.

5.13.3 Supporting information

Summarized results for bromoform are presented for each Public Health Unit in Appendix 2.3.


0

10

20

30

40

0-10% -20% -30% -40% -50%

per cent of MAV



5.14 Chlorate 5.14.1 Summary information

Synonyms None


50% MAV 0.15 mg/L

Remarks (from DWSNZ:2000) PMAV, disinfection must never be compromised

Assessed in the P2 Programme? Yes: M1 and M2 for all zones disinfected with

sodium or calcium hypochlorite



130 samples

Number of community drinking-water zones with chlorate identified at > 50% MAV

32

Population served by community drinking-water zones with chlorate identified at greater than 50% MAV

423,526

Population served by community drinking-water zones with chlorate identified at greater than MAV, i.e. health significant concentrations

1,505 (8 zones)



Do the data suggest that chlorate is found more frequently in surface, ground or rain water


between the disinfectant added at the treatment plant, and precursors contained within the source water. They are only an issue for those supplies that are

disinfected.

Do the data suggest that chlorate is found more frequently in large, small or school supplies

No

5.14.2 Detections up to 50% MAV Chlorate was detected in 64 zones (7.5% of those assessed). A representation of the frequency with which detections to 50% MAV were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for chlorate. 5.14.3 Supporting information In terms of disinfection by-products identified at greater than 50% of their MAV, chlorate affects the greatest population (423,526 people). This is largely a result of its identification in water from one large treatment plant,


0

5

10

15

0-10% -20% -30% -40% -50%

per cent of MAV


which supplies water to a number of distribution zones that serve large populations. The MAV for chlorate was introduced in the DWSNZ:2000, i.e. recently, and this means that water suppliers have not had the same level of opportunity, in terms of time, to develop strategies to deal with the presence of chlorate in their water supplies as they have done for other determinands. Summarized results for chlorate are presented for each Public Health Unit in Appendix 2.4.



5.15 Chlorite 5.15.1 Summary information Synonyms None


50% MAV 0.15 mg/L

Remarks (from DWSNZ:2000) PMAV, disinfection must never be compromised

Assessed in the P2 Programme? No (no treatment plants that use chlorine

dioxide as a disinfectant have been assessed)



Number of community drinking-water zones with chlorite identified at > 50% MAV 0

Population served by community drinking-water zones with chlorite identified at greater than 50% MAV

0

Population served by community drinking-water zones with chlorite identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that chlorite is found more frequently in surface, ground or rain water

N/A

Do the data suggest that chlorite is found more frequently in large, small or school supplies

N/A

Comment Chlorite has not been assessed.


5.16 Chloroform THM 5.16.1 Summary information

Synonyms Trichloromethane


50% MAV 0.1 mg/L


Assessed in the P2 Programme? Yes: M1 and M2 for all disinfected (chlorinated and

ozonated) zones



511 samples

Number of community drinking-water zones with chloroform identified at > 50% MAV

2

Population served by community drinking-water zones with chloroform identified at greater than 50% MAV

540

Population served by community drinking-water zones with chloroform identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that chloroform is found more frequently in surface, ground or rain water



disinfected.

Do the data suggest that chloroform is found more frequently in large, small or school supplies

No


Chloroform was detected in 374 zones (44% of those assessed, 73% of those disinfected). A representation of the frequency with which detections to 50% were found in shown in the bar chart below.

Detections are expressed in terms of their percentage of the MAV for chloroform.

Chloroform is a member of the trihalomethane (THM) ‘family’, and as such is included in the determinand ‘THM’ which is included later in this chapter.


Summarized results for chloroform are presented for each Public Health Unit in Appendix 4.5.


0

100

200

300

400

0-10% -20% -30% -40% -50%

per cent of MAV



5.17 Cyanogen chloride (as CN) 5.17.1 Summary information Synonyms None


50% MAV 0.04 mg/L


Assessed in the P2 Programme? Yes: M1 and M2 for chlorinated zones


Number of community drinking-water zones with cyanogen chloride (as CN) identified at > 50% MAV

0

Population served by community drinking-water zones with cyanogen chloride (as CN) identified at greater than 50% MAV

0

Population served by community drinking-water zones with cyanogen chloride (as CN) identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that cyanogen chloride (as CN) is found more frequently in surface, ground or rain water

No

Do the data suggest that cyanogen chloride (as CN) is found more frequently in large, small or school supplies

No

5.17.2 Detections up to 50% MAV A review of the disinfection by-product results for the 1995/96 Programme Round showed that cyanogen chloride had not been detected in any samples taken during that year. Furthermore, examination of literature available concerning the stability of the cyanogen chloride under water treatment conditions indicated that analysis is required within a few hours of sampling, even with sample dechlorination, if there is to be any chance of detecting the compound. As logistics do not allow such a short interval between sampling and analysis, this disinfection by-product was removed from the suite of analyses undertaken in the Programme from the 1996/97 Round onwards. (Nokes and Davies, 2000)


5.18 Dibromoacetonitrile 5.18.1 Summary information Synonyms Dibromoethanenitrile


50% MAV 0.1 mg/L


Assessed in the P2 Programme? Yes: M1 and M2 for all disinfected (chlorinated

and ozonated) zones until when?



209 samples

Number of community drinking-water zones with dibromoacetonitrile identified at > 50% MAV

0

Population served by community drinking-water zones with dibromoacetonitrile identified at greater than 50% MAV

0

Population served by community drinking-water zones with dibromoacetonitrile identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that dibromoacetonitrile is found more frequently in surface, ground or rain water




Do the data suggest that dibromoacetonitrile is found more frequently in large, small or school supplies

No

5.18.2 Detections up to 50% MAV Dibromoacetonitrile was detected in 7 zones. Because none of the concentrations of dibromoacetonitrile were close to 50% of MAV, analysis for this determinand was halted in the 1996/97 P2 Programme Round. As such, dibromoacetonitrile was not assessed in zones investigated after this time. 5.18.3 Supporting information Summarized results for dibromoacetonitrile are presented for each Public Health Unit in Appendix 2.6.


5.19 Dibromochloromethane THM 5.19.1 Summary information Synonyms Chlorodibromomethane


50% MAV 0.05 mg/L



zones



511 samples

Number of community drinking-water zones with dibromochloromethane identified at > 50% MAV

0

Population served by community drinking-water zones with dibromochloromethane identified at greater than 50% MAV

0

Population served by community drinking-water zones with dibromochloromethane identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd – 0.028


Do the data suggest that dibromochloromethane is found more frequently in surface, ground or rain water




Do the data suggest that dibromochloromethane is found more frequently in large, small or school supplies

No

5.19.2 Detections up to 50% MAV There have been no detections of dibromochloromethane. 5.19.3 Supporting information Summarized results for dibromochloromethane are presented for each Public Health Unit in Appendix 2.7.



5.20 Dichloroacetic acid HAA 5.20.1 Summary information Synonyms Dichloroacetic acid


50% MAV 0.025 mg/L



zones



488 samples

Number of community drinking-water zones with dichloroacetic acid HAAidentified at > 50% MAV

38

Population served by community drinking-water zones with dichloroacetic acid HAAidentified at greater than 50% MAV

68,123

Population served by community drinking-water zones with dichloroacetic acid HAAidentified at greater than MAV, i.e. health significant concentrations

3,160 (5 zones)



Do the data suggest that dichloroacetic acid HAAis found more frequently in surface, ground or rain water

Impossible to determine, unless disinfection status is included in the analysis

Do the data suggest that dichloroacetic acid HAAis found more frequently in large, small or school supplies

No

5.20.2 Detections up to 50% MAV Dichloroacetic acid was detected in 203 zones (24% of those assessed, 42% of those zones sampled). A representation of the frequency with which detections to 50% were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for dichloroacetic acid. Dichloroacetic acid is a member of the haloacetic acid (HAA) ‘family’, and as such is included in the determinand ‘HAA’ which is included later in this chapter. 5.20.3 Supporting information Summarized results for dichloroacetic acid are presented for each Public Health Unit in Appendix 2.8.


020406080

100120

0-10% -20% -30% -40% -50%

per cent MAV



5.21 Dichloroacetonitrile


Synonyms Dichloroethanenitrile


50% MAV 0.05 mg/L


Assessed in the P2 Programme? Yes: M1 and M2 for all disinfected (chlorinated and

ozonated) zones



209 samples

Number of community drinking-water zones with dichloroacetonitrile identified at > 50% MAV

0

Population served by community drinking-water zones with dichloroacetonitrile identified at greater than 50% MAV

0

Population served by community drinking-water zones with dichloroacetonitrile identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that dichloroacetonitrile is found more frequently in surface, ground or rain water



disinfected.

Do the data suggest that dichloroacetonitrile is found more frequently in large, small or school supplies

No


Dichloroacetonitrile has been detected in 29 zones (3% of those assessed). A representation of the frequency with which detections to 50% were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for dichloroacetonitrile. Because none of the concentrations of

dichloroacetonitrile were close to 50% MAV, analysis for this determinand was halted in the 1996/97 P2 Programme Round. As such, dichloroacetonitrile was not assessed in zones investigated after this time.

5.21.3 Supporting information Summarized results for dichloroacetonitrile are presented for each Public Health Unit in Appendix 2.9.


0

10

20

30

40

0-10% -20% -30% -40% -50%

per cent MAV


5.22 Dichloromethane 5.22.1 Summary information Synonyms None


50% MAV 0.01 mg/L





332 samples

Number of community drinking-water zones with dichloromethane identified at > 50% MAV

0

Population served by community drinking-water zones with dichloromethane identified at greater than 50% MAV

0

Population served by community drinking-water zones with dichloromethane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that dichloromethane is found more frequently in surface, ground or rain water




Do the data suggest that dichloromethane is found more frequently in large, small or school supplies

No

5.22.2 Detections up to 50% MAV There have been no detections of dichloromethane. The limit of detection is high, relative to the MAV (40% of MAV). 5.22.3 Supporting information Summarized results for dichloromethane are presented for each Public Health Unit in Appendix 2.10. Comment Dichloromethane is also listed within the ‘Other Organics’ chapter.


5.23 Formaldehyde 5.23 Summary information Synonyms Methanal

Isomers None listed in DWSNZ

Maximum Acceptable Value (MAV) 1 mg/L

50% MAV 0.5 mg/L





Number of community drinking-water zones with formaldehyde identified at > 50% MAV

0

Population served by community drinking-water zones with formaldehyde identified at greater than 50% MAV

0

Population served by community drinking-water zones with formaldehyde identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that formaldehyde is found more frequently in surface, ground or rain water

No

Do the data suggest that formaldehyde is found more frequently in large, small or school supplies

No

5.23.2 Detections up to 50% MAV There have been no detections of formaldehyde. Formaldehyde is used in various industries, and is also a disinfection by-product formed through the reaction between ozone and naturally occurring organic substances (MoH 1995b). Formaldehyde was analysed in samples from four zones.


5.24 Monochloramine 5.24.1 Summary information Synonyms None


50% MAV 1.5 mg/L


Assessed in the P2 Programme? No: Has to be measured in the field


Number of community drinking-water zones with monochloramine identified at > 50% MAV

0

Population served by community drinking-water zones with monochloramine identified at greater than 50% MAV

0

Population served by community drinking-water zones with monochloramine identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that monochloramine is found more frequently in surface, ground or rain water

N/A

Do the data suggest that monochloramine is found more frequently in large, small or school supplies

N/A

Comment Monochloramine has not been assessed.


5.25 Trichloroacetaldehyde/chloral hydrate 5.25.1 Summary information

Synonyms Trichloroethanal


50% MAV 0.005 mg/L


Assessed in the P2 Programme? Yes: M1 and M2 for all chlorinated zones


Number of community drinking-water zones with trichloroacetaldehyde/chloral hydrate identified at > 50% MAV

75

Population served by community drinking-water zones with trichloroacetaldehyde/chloral hydrate identified at greater than 50% MAV

233,249

Population served by community drinking-water zones with trichloroacetaldehyde/chloral hydrate identified at greater than MAV, i.e. health significant concentrations

46,975 (17 zones)



Do the data suggest that trichloroacetaldehyde/chloral hydrate is found more frequently in surface, ground or rain water




Do the data suggest that trichloroacetaldehyde/chloral hydrate is found more frequently in large, small or school supplies

No

5.25.2 Detections up to 50% MAV Trichloroacetaldehyde has been detected in 195 zones (23% of those assessed, 40% of those zones from which samples were taken). A representation of the frequency with which detections to 50% were found is shown in the bar chart below. Detections are expressed in terms of their percentage of the MAV for trichloroacetaldehyde. 5.25.3 Supporting information Summarized results for trichloroacetaldehyde/choral hydrate are presented for each Public Health Unit in Appendix 2.11.


0

20

40

60

80

0-10% -20% -30% -40% -50%

per cent MAV


5.26 Trichloroacetic acid HAA


Synonyms Trichloroethanoic acid


50% MAV 0.05 mg/L





488 samples

Number of community drinking-water zones with trichloroacetic acid HAAidentified at > 50% MAV

23

Population served by community drinking-water zones with trichloroacetic acid HAAidentified at greater than 50% MAV

41,100

Population served by community drinking-water zones with trichloroacetic acid HAAidentified at greater than MAV, i.e. health significant concentrations

240 (1 zone)



Do the data suggest that trichloroacetic acid HAAis found more frequently in surface, ground or rain water




Do the data suggest that trichloroacetic acid HAA is found more frequently in large, small or school supplies

No

5.26.2 Detections up to 50% MAV Trichloroacetic acid has been detected in 209 zones (24% of those assessed, 43% of those zones from which samples were taken). A representation of the frequency with which detections to 50% were found in shown in the bar chart below.

Detections are expressed in terms of their percentage of the MAV for bromoform. Trichloroacetic acid is a member of the haloacetic acid (HAA) ‘family’, and as such is included in the determinand ‘HAA’ which is included later in this chapter.


Summarized results for trichloroacetic acid are presented for each Public Health Unit in Appendix 2.12.


020406080

100120

0-10% -20% -30% -40% -50%

per cent MAV



5.27 Trichloroacetonitrile 5.27.1 Summary information Synonyms Trichloroethanenitrile


50% MAV 0.0005 mg/L





209 samples

Number of community drinking-water zones with trichloroacetonitrile identified at > 50% MAV

0

Population served by community drinking-water zones with trichloroacetonitrile identified at greater than 50% MAV

0

Population served by community drinking-water zones with trichloroacetonitrile identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that trichloroacetonitrile is found more frequently in surface, ground or rain water




Do the data suggest that trichloroacetonitrile is found more frequently in large, small or school supplies

No

5.27.2 Detections up to 50% MAV There have been no detections of trichloroacetonitrile. Because none of the samples taken had any trichloroacetonitrile detected, analysis for this determinand was halted in the 1996/97 P2 Programme Round. As such, trichloroacetonitrile was not assessed in zones looked at after this time. 5.27.3 Supporting information Summarized results for trichloroacetonitrile are presented for each Public Health Unit in Appendix 2.13.


5.28 Trihalomethanes (THMs) 5.28.1 Summary information Synonyms

Maximum Acceptable Value (MAV)

50% MAV

Remarks (from DWSNZ:2000) The sum of the ratio of the concentration of each to its respective MAV should not exceed 1 (50% = 0.5).

Assessed in the P2 Programme? Calc.



This determined is a figure calculated from the results from the individual trihalomethanes

Number of community drinking-water zones with trihalomethanes identified at > 50% MAV

34

Population served by community drinking-water zones with trihalomethanes identified at greater than 50% MAV

76,123

Population served by community drinking-water zones with trihalomethanes identified at greater than MAV, i.e. health significant concentrations

4,900 (2 zones)

Range of P2 Programme results

Median of P2 Programme results

Do the data suggest that trihalomethanes is found more frequently in surface, ground or rain water




Do the data suggest that trihalomethanes is found more frequently in large, small or school supplies

No

5.28.2 Supporting information Summarized results for trihalomethanes are presented for each Public Health Unit in Appendix 2.14.



5.29 Haloacetic acids (HAAs) 5.29.1 Summary information

Synonyms

Maximum Acceptable Value (MAV)

50% MAV

Remarks (from DWSNZ:2000) The sum of the ratio of the concentration of each to its respective MAV should not exceed 1 (50% = 0.5).

Assessed in the P2 Programme? Calc.


Number of community drinking-water zones with haloacetic acids (HAAs)identified at > 50% MAV

71

Population served by community drinking-water zones with haloacetic acids (HAAs)identified at greater than 50% MAV

161,980

Population served by community drinking-water zones with haloacetic acids (HAAs)identified at greater than MAV, i.e. health significant concentrations

55,184 (28 zones)

Range of P2 Programme results

Median of P2 Programme results

Do the data suggest that haloacetic acids (HAAs)is found more frequently in surface, ground or rain water




Do the data suggest that haloacetic acids (HAAs)is found more frequently in large, small or school supplies

No

5.29.2 Supporting information Summarized results for haloacetic acids are presented for each Public Health Unit in Appendix 2.15.



5.30 Bromochloroacetic acid 5.30.1 Summary information

Synonyms None

Maximum Acceptable Value (MAV) No MAV

50% MAV No MAV



Limit of detection for samples taken as part of the P2 Programme 0.005 mg/L


488 samples

Number of community drinking-water zones with bromochloroacetic acid identified at > 50% MAV

N/A

Population served by community drinking-water zones with bromochloroacetic acid identified at greater than 50% MAV

N/A

Population served by community drinking-water zones with bromochloroacetic acid identified at greater than MAV, i.e. health significant concentrations

N/A

Range of P2 Programme results nd – 0.023 mg/l


Do the data suggest that bromochloroacetic acid is found more frequently in surface, ground or rain water




Do the data suggest that bromochloroacetic acid is found more frequently in large, small or school supplies

No

5.30.2 Detections up to 50% MAV Bromochloroacetic acid has been detected in 51 zones (6% of those assessed, 10% of those zones from which samples were taken). A representation of the frequency with which detections were found is shown in the bar chart below. 5.30.3 Supporting information Summarized results for bromochloroacetic acid are presented for each Public Health Unit in Appendix 2.16.

All detections

01020304050

0 - 5 to 10 to 15 to 20 to 25

ug/L

num

ber

of z

ones


5.31 Dibromoacetic acid 5.31.1 Summary information Synonyms None


50% MAV No MAV





488 samples

Number of community drinking-water zones with dibromoacetic acididentified at > 50% MAV

N/A

Population served by community drinking-water zones with dibromoacetic acididentified at greater than 50% MAV

N/A

Population served by community drinking-water zones with dibromoacetic acididentified at greater than MAV, i.e. health significant concentrations

N/A



Do the data suggest that dibromoacetic acidis found more frequently in surface, ground or rain water




Do the data suggest that dibromoacetic acidis found more frequently in large, small or school supplies

No

5.31.2 Detections up to 50% MAV Dibromoacetic acid has been detected in 12 zones (1% of those assessed, 2.5% of those zones from which samples were taken). A representation of the frequency with which detections were found is shown in the bar chart below. 5.31.3 Supporting information Summarized results for dibromoacetic acid are presented for each Public Health Unit in Appendix 2.17.

All detections

0

2

4

6

0 - 3 to 6 to 9 to 12 to 15

ug/L

Num

ber

of z

ones


5.32 Monochloroacetic acid 5.32.1 Summary information Synonyms Chloroacetic acid (chloroacetic acid

(chloroethanoic acid)


50% MAV No MAV

Remarks (from DWSNZ:2000) This is a determinand for which health concerns have been raised but for which no MAV can be set, because there are no adequate data.




488 samples

Number of community drinking-water zones with monochloroacetic acididentified at > 50% MAV

N/A

Population served by community drinking-water zones with monochloroacetic acididentified at greater than 50% MAV

N/A

Population served by community drinking-water zones with monochloroacetic acididentified at greater than MAV, i.e. health significant concentrations

N/A



Do the data suggest that monochloroacetic acidis found more frequently in surface, ground or rain water




Do the data suggest that monochloroacetic acidis found more frequently in large, small or school supplies

No

5.32.2 Detections up to 50% MAV Monochloroacetic acid has been detected in three zones (0.3% of those assessed, 0.6% of those zones from which samples were taken). 5.32.3 Supporting information Summarized results for monochloroacetic acid are presented for each Public Health Unit in Appendix 2.18.


5.33 Bromochloroacetonitrile 5.33.1 Summary information Synonyms Bromochloroethanenitrile


50% MAV No MAV

Remarks (from DWSNZ:2000) This is a determinand for which health concerns have been raised but for which no MAV can be set, because there are no adequate data




209 samples

Number of community drinking-water zones with bromochloroacetonitrile identified at > 50% MAV

N/A

Population served by community drinking-water zones with bromochloroacetonitrile identified at greater than 50% MAV

N/A

Population served by community drinking-water zones with bromochloroacetonitrile identified at greater than MAV, i.e. health significant concentrations

N/A



Do the data suggest that bromochloroacetonitrile is found more frequently in surface, ground or rain water




Do the data suggest that bromochloroacetonitrile is found more frequently in large, small or school supplies

No

5.33.2 Detections up to 50% MAV Bromochloroacetonitrile has been detected in one zone (0.1% of those assessed, 0.2% of those zones from which samples were taken). 5.33.3 Supporting information Summarized results for bromochloroacetonitrile are presented for each Public Health Unit in Appendix 2.19.


5.34 Bromochloromethane 5.34.1 Summary information

Synonyms None


50% MAV No MAV





173 samples

Number of community drinking-water zones with bromochloromethaneidentified at > 50% MAV

N/A

Population served by community drinking-water zones with bromochloromethaneidentified at greater than 50% MAV

N/A

Population served by community drinking-water zones with bromochloromethaneidentified at greater than MAV, i.e. health significant concentrations

N/A



Do the data suggest that bromochloromethaneis found more frequently in surface, ground or rain water




Do the data suggest that bromochloromethaneis found more frequently in large, small or school supplies

No

5.34.2 Detections up to 50% MAV Bromochloromethane has been detected in 12 zones (1% of those assessed, 7% of those zones from which samples were taken). A representation of the frequency with which detections were found is shown in the bar chart below. 5.34.3 Supporting information Summarized results for bromochloromethane are presented for each Public Health Unit in Appendix 2.20.

All detections

02468

1012

0 - 0.5 to 1.0 to 1.5

ug/L

Num

ber

of z

ones


5.35 Dibromomethane 5.35.1 Summary information Synonyms None


50% MAV No MAV


Assessed in the P2 Programme? Yes: M1 and M2 from all chlorinated zones



173 samples

Number of community drinking-water zones with dibromomethane identified at > 50% MAV

N/A

Population served by community drinking-water zones with dibromomethane identified at greater than 50% MAV

N/A

Population served by community drinking-water zones with dibromomethane identified at greater than MAV, i.e. health significant concentrations

N/A



Do the data suggest that dibromomethane is found more frequently in surface, ground or rain water




Do the data suggest that dibromomethane is found more frequently in large, small or school supplies

No

5.35.2 Detections up to 50% MAV Dibromomethane has been detected in six zones (0.7% of those assessed, 3.5% of those zones from which samples were taken). 5.35.3 Supporting information Summarized results for dibromomethane are presented for each Public Health Unit in Appendix 2.21.


5.36 1,1-Dichloropropan-2-one 5.36.1 Summary information Synonyms None listed in DWSNZ


50% MAV No MAV





491 samples


N/A


N/A


N/A








No

5.36.2 Detections up to 50% MAV 1,1-Dichloropropan-2-one has been detected in four zones (0.5% of those assessed, 0.8% of those zones sampled). 5.36.3 Supporting information Summarized results for 1,1-dichloropropan-2-one are presented for each Public Health Unit in Appendix 2.22.


5.37 1,1,1-Trichloropropan-2-one 5.37.1 Summary information Synonyms None listed in DWSNZ


50% MAV No MAV





491 samples


N/A


N/A


N/A








No

5.37.2 Detections up to 50% MAV 1,1,1-Trichloroprpan-2-one has been detected in 50 zones (0.5% of those assessed, 0.8% of those zones sampled). A representation of the frequency with which detections were found is shown in the bar chart below. 5.37.3 Supporting information Summarized results for 1,1,1-trichloropropan-2-one are presented for each Public Health Unit in Appendix 2.23.

All detections

010203040

0 - 2 to 4 to 6 to 8 to 10

ug/L

Num

ber o

f zon

es


CHAPTER 6: PESTICIDES 6.1 Introduction This chapter reports on detections of pesticides in New Zealand’s community drinking-water supplies. In the context of this report, pesticides are limited to chemicals that are listed in Table 14.4 of the Drinking-Water Standards for New Zealand:2000 (DWSNZ:2000) (MoH 2000a). It is acknowledged that some chemicals that are (or used to be) used as pesticides, are also used for other purposes. For example, hexachlorobenzene, which was widely used as a pesticide, has also been used to make fireworks, ammunition, and synthetic rubber (although whether it has been used for these purposes in New Zealand is unknown). Fifty four pesticides are allocated Maximum Acceptable Values (MAVs) or Provisional Maximum Acceptable Values (PMAVs) in Table 14.4 of the DWSNZ:2000 (MoH 2000a). Drinking-water supplies have been investigated for the presence of thirty six pesticides and results are reported in this chapter. Pesticides cover a range of chemical families. The uses, along with the chemical family, are given for each pesticide in Table 6.1.

Table 6.1 Use and chemical families for the pesticides included in the DWSNZ:2000 = Yes = No Pesticide name MAV

mg/L New in

DWSNZ:2000 Presence

investigated? Use Chemical family

Alachlor 0.02 Herbicide Organo nitrogen herbicide

Aldicarb 0.01 Insecticide Carbamate

Aldrin + Dieldrin 0.00003 Insecticide Organochlorine pesticide

Atrazine 0.002 Herbicide Organo nitrogen herbicide

Azinphos methyl 0.004 Insecticide Organophosphate insecticide

Bentazone (old MAV = 0.03 mg/L)

0.4 Herbicide Acid herbicide

Bromacil 0.4 Herbicide Uracil herbicide

Carbofuran (old MAV = 0.006 mg/L)

0.008 Control of insects, mites, and nematodes

Carbamate

Chlordane 0.0002 Insecticide Organochlorine pesticide

Chlorpyriphos 0.07 Insecticide Organophosphorus pesticide

Chlortoluron 0.04 Herbicide Phenylurea herbicide

Cyanazine 0.0007 Herbicide Organonitrogen herbicide

2,4-D (old MAV = 0.03 mg/L) 0.04 Herbicide Acid herbicide

2,4-DB 0.1 Herbicide Acid herbicide

DDT + isomers 0.002 Insecticide Organochlorine pesticide

Diazinon 0.01 Insecticide Organophosphorus pesticide

1,2-Dibromo-3-chloropropane 0.001 Nematicide Halogenated alkane

1,2-Dichloropropane 0.02 Insecticide Halogenated alkane


Pesticide name MAV mg/L

New in DWSNZ:2000

Presence investigated?

Use Chemical family

1,3-Dichloropropene 0.02 Nematicide Halogenated alkene

Dichlorprop 0.1 Herbicide Acid herbicide

Diquat 0.01 Herbicide Quaternary ammonium herbicide

Diuron 0.02 Herbicide Phenylurea herbicide

Fenoprop 0.01 Herbicide Acid herbicide

Heptachlor and heptachlor epoxide

0.00004 Insecticide Organochlorine pesticide

Hexachlorobenzene 0.001 Fungicide Organochlorine pesticide

Hexazinone 0.4 Herbicide Organonitrogen herbicide

Isoproturon 0.01 Herbicide Phenylurea herbicide

Lindane 0.002 Insecticide Organochlorine pesticide

MCPA 0.002 Herbicide Acid herbicide

Mecoprop 0.01 Herbicide Acid herbicide

Metalaxyl 0.1 Fungicide Benzenoid

Methoxychlor 0.02 Insecticide Organochlorine pesticide

Metolachlor 0.01 Herbicide Chloroacetanilide herbicides

Metribuzin 0.07 Herbicide Organonitrogen herbicide

Molinate 0.007 Herbicide Organonitrogen herbicide

Oryzalin 0.4 Herbicide Dinitroaniline herbicides

Oxadiazon 0.2 Herbicide Oxadiazole

Pendimethalin 0.02 Herbicide Organonitrogen herbicide

Pentachlorophenol 0.01 Insecticide and fungicide

Chlorophenol

Permethrin 0.02 Insecticide Organochlorine pesticide

Picloram 0.2 Herbicide Pyridine compound

Pirimiphos methyl 0.1 Insecticide Organophosphorus pesticide

Pirimisulfuron methyl 0.9 Insecticide Organophosphorus pesticide

Procymidone 0.7 Fungicide Organochlorine pesticide

Propanil 0.02 Herbicide Organonitrogen herbicide

Propazine 0.07 Herbicide Organonitrogen herbicide

Pyridate 0.1 Herbicide Pyridazine herbicides

Simazine 0.002 Herbicide Organonitrogen herbicide

2,4,5-T 0.01 Herbicide Acid herbicide

Terbuthylazine (old MAV = 0.02 mg/L)

0.008 Herbicide Organonitrogen herbicide

Thiabendazole 0.4 Fungicide Benzimidazole

Triclopyr 0.1 Herbicide Acid herbicide

Trifluralin 0.03 Herbicide Organonitrogen herbicide

1080 (old MAV = 0.005 mg/L) 0.0035 Possum control Sodium monofluoroacetate


6.2 Origins of the analytical data 6.2.1 P2 Programme: Baseline sampling The first set of sampling undertaken in a P2 Programme assessment is termed the ‘Baseline’ sampling round. Pesticides are not included in the Baseline sampling round. 6.2.2 P2 Programme: M1 and M2 sampling The first and second monitoring rounds (M1 and M2), which follow the Baseline sampling round for each zone, are targeted towards those determinands that have been identified as having the potential to be present in the zone at health significant concentrations. Results from the Baseline sampling, along with information collected through questionnaires are used to select which determinands to include in the targeted sampling. Pesticides are selected for analysis in this way. 6.3 Summary of results Table 6.2 presents a summary of pesticide results. Further details relating to each determinand can be found by referring to the page dedicated to it within this chapter.


Table 6.2 Summary table for pesticides = Yes = No Pesticide name MAV mg/L Assessed Detected > 50% MAV Transgression

Alachlor 0.02 Aldicarb 0.01 Aldrin + Dieldrin 0.00003 3 zones 2 zones Atrazine 0.002 Azinphos methyl 0.004 Bentazone 0.4 Bromacil 0.4 Carbofuran 0.008 Chlordane 0.0002 Chlorpyriphos 0.07 Chlortoluron 0.04 Cyanazine 0.0007 2,4-D 0.04 2,4-DB 0.1 DDT + isomers 0.002 Diazinon 0.01 1,2-Dibromo-3-chloropropane 0.001 1,2-Dichloropropane 0.02 1,3-Dichloropropene 0.02 Dichlorprop 0.1 Diquat 0.01 Diuron 0.02 Fenoprop 0.01 Heptachlor and heptachlor epoxide 0.00004 Hexachlorobenzene 0.001 Hexazinone 0.4 Isoproturon 0.01 Lindane 0.002 MCPA 0.002 Mecoprop 0.01 Metalaxyl 0.1 Methoxychlor 0.02 Metolachlor 0.01 Metribuzin 0.07 Molinate 0.007 Oryzalin 0.4 Oxadiazon 0.2 Pendimethalin 0.02 Pentachlorophenol 0.01 Permethrin 0.02


Pesticide name MAV mg/L Assessed Detected > 50% MAV Transgression

Picloram 0.2 Pirimiphos methyl 0.1 Pirimisulfuron methyl 0.9 Procymidone 0.7 Propanil 0.02 Propazine 0.07 Pyridate 0.1 Simazine 0.002 1 zone 2,4,5-T 0.01 1 zone Terbuthylazine 0.008 2 zones Thiabendazole 0.4 Triclopyr 0.1 2 zones Trifluralin 0.03 1080 0.0035 Table 6.3 Pesticides detected in community drinking-water supplies Determinand Use Detections Limit of detection Range of detections

expressed as a % of MAV No. of zones Population mg/L % of MAV

Dieldrin Insecticide 3 7,860 0.00001 33% 33 – 100%

Simazine Herbicide 1 200 0.0001 5% 10.0%

2,4,5-T Herbicide 1 120 0.0001 1% 2.0%

Terbuthylazine Herbicide 2 280 0.0002 2.5% 2.5 – 25%

Triclopyr Herbicide 2 840 0.0001 0.1% 0.1 – 0.6%

6.4 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) Thirty six pesticides have been assessed. No transgressions of the MAV have been identified. Concentrations that exceeded 50% of the MAV have been identified for one determinand only - dieldrin (in two zones). These two zones affect a total population of 360 people. 6.5 Detections to 50% MAV Five different pesticides have been detected. These are shown in Table 6.3. The limits of detection for dieldrin (33% MAV) 1,2-dibromo-3-chloropropane (50% of MAV), and heptachlor and heptachlor epoxide (25% MAV) are of note. 6.6 Geographical distribution There is no relationship between pesticide detections and geographical distributions apparent from the small number of detections.


6.7 Source types Because pesticides were detected in so few zones, it has not been possible to determine any relationship between source type (rain, surface or groundwater) and the detection of pesticides. 6.8 Unassessed zones Unassessed zones may have different characteristics to the community drinking-water supplies assessed through the P2 Programme. Pesticide detections reported by Close in the national surveys of pesticides in groundwater have been more frequent than for the supplies reported here, and this may result from the greater vulnerability to contamination of the wells selected for his survey (Close 1996, Close and Rosen 1999).


6.9 Alachlor 6.9.1 Summary information Synonyms 2-chloro-2',6'-dimethyl-N-methoxymethyl

acetanilide



50% MAV 0.01 mg/L

Remarks (from DWSNZ:2000) For excess lifetime cancer risk of 10 -5




Number of community drinking-water zones with alachlor identified at > 50% MAV 0

Population served by community drinking-water zones with alachlor identified at greater than 50% MAV

0

Population served by community drinking-water zones with alachlor identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd - nd


Do the data suggest that alachlor is found more frequently in surface, ground or rain water

No

Do the data suggest that alachlor is found more frequently in large, small or school supplies

No

6.9.2 Detections up to 50% MAV There have been no detections of alachlor.


6.10 Aldicarb 6.10.1 Summary information Synonyms 2-methyl-2-(methylthio) propionaldehyde-O-

methylcarbamoyloxime



50% MAV 0.005 mg/L




Number of community drinking-water zones with aldicarb identified at > 50% MAV 0

Population served by community drinking-water zones with aldicarb identified at greater than 50% MAV

0

Population served by community drinking-water zones with aldicarb identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that aldicarb is found more frequently in surface, ground or rain water

N/A

Do the data suggest that aldicarb is found more frequently in large, small or school supplies

N/A

Comment Aldicarb has not been assessed.


6.11 Aldrin + Dieldrin 6.11.1 Summary information Synonyms ,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-

hexahydro-1,4: 5,8-dimethanonaphthalene & 1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydroendo, exo-1,4:5,8-dimethanonaphthalene



50% MAV 0.000015 mg/L





Number of community drinking-water zones with aldrin + dieldrin identified at > 50% MAV

2

Population served by community drinking-water zones with aldrin + dieldrin identified at greater than 50% MAV

360

Population served by community drinking-water zones with aldrin + dieldrin identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd – 0.00003 mg/L/L


Do the data suggest that aldrin + dieldrin is found more frequently in surface, ground or rain water

No

Do the data suggest that aldrin + dieldrin is found more frequently in large, small or school supplies

No

6.11.2 Detections up to 50% MAV Dieldrin has been detected in 3 zones (0.3% of those assessed) at concentrations ranging from 0.00001 to 0.00003 mg/L (33 – 100% of MAV). Summarized results for dieldrin are presented for each Public Health Unit in Appendix 3.1.


6.12 Atrazine 6.12.1 Summary information Synonyms 6-chloro-N-ethyl-N’-(1-methylethyl)-1,3,5-

triazine-2,4-diamine



50% MAV 0.001 mg/L





Number of community drinking-water zones with atrazine identified at > 50% MAV 0

Population served by community drinking-water zones with atrazine identified at greater than 50% MAV

0

Population served by community drinking-water zones with atrazine identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd-nd


Do the data suggest that atrazine is found more frequently in surface, ground or rain water

No

Do the data suggest that atrazine is found more frequently in large, small or school supplies

No

6.12.2 Detections up to 50% MAV There have been no detections of atrazine.


6.13 Azinphos methyl

6.13.1 Summary information Synonyms S-(3,4-dihydro-4-oxobenzo(d) (1,2,3)-trizin-3-

ylmethyl) O,O-dimethyl phosphorodithioate



50% MAV 0.002 mg/L





Number of community drinking-water zones with azinphos methyl identified at > 50% MAV

0

Population served by community drinking-water zones with azinphos methyl identified at greater than 50% MAV

0

Population served by community drinking-water zones with azinphos methyl identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that azinphos methyl is found more frequently in surface, ground or rain water

N/A

Do the data suggest that azinphos methyl is found more frequently in large, small or school supplies

N/A

Comment Azinphos methyl has not been assessed.


6.14 Bentazone 6.14.1 Summary information Synonyms 3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-

4(3H)-one-2,2-dioxide or bendioxide



50% MAV 0.2 mg/L





Number of community drinking-water zones with bentazone identified at > 50% MAV 0

Population served by community drinking-water zones with bentazone identified at greater than 50% MAV

0

Population served by community drinking-water zones with bentazone identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that bentazone is found more frequently in surface, ground or rain water

No

Do the data suggest that bentazone is found more frequently in large, small or school supplies

No

6.14.2 Detections up to 50% MAV There have been no detections of bentazone.


6.15 Bromacil 6.15.1 Summary information Synonyms 5-bromo-3-sec-butyl-6-methyluracil



50% MAV 0.2 mg/L





Number of community drinking-water zones with bromacil identified at > 50% MAV 0

Population served by community drinking-water zones with bromacil identified at greater than 50% MAV

0

Population served by community drinking-water zones with bromacil identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that bromacil is found more frequently in surface, ground or rain water

N/A

Do the data suggest that bromacil is found more frequently in large, small or school supplies

N/A

Comment Bromacil has not been assessed.


6.16 Carbofuran 6.16.1 Summary information Synonyms 2,3-dihydro-2,2-dimethyl-7-benzofuranol

methylcarbamate



50% MAV 0.004 mg/L




Total number of samples analysed for this determinand in Phase 1 of the P2 Programme 0

Number of community drinking-water zones with carbofuran identified at > 50% MAV 0

Population served by community drinking-water zones with carbofuran identified at greater than 50% MAV

0

Population served by community drinking-water zones with carbofuran identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that carbofuran is found more frequently in surface, ground or rain water

N/A

Do the data suggest that carbofuran is found more frequently in large, small or school supplies

N/A

Comment Carbofuran has not been assessed.


6.17 Chlordane 6.17.1 Summary information Synonyms 1,2,4,5,6,7,8,8-octachloro-2,3,3a, 4,7,7a-

hexahydro-4,7-methano-1H-indene



50% MAV 0.0001 mg/L





Number of community drinking-water zones with chlordane identified at > 50% MAV 0

Population served by community drinking-water zones with chlordane identified at greater than 50% MAV

0

Population served by community drinking-water zones with chlordane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that chlordane is found more frequently in surface, ground or rain water

No

Do the data suggest that chlordane is found more frequently in large, small or school supplies

No

6.17.2 Detections up to 50% MAV There have been no detections of chlordane.


6.18 Chlorpyriphos 6.18.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.035 mg/L





Number of community drinking-water zones with chlorpyriphos identified at > 50% MAV

0

Population served by community drinking-water zones with chlorpyriphos identified at greater than 50% MAV

0

Population served by community drinking-water zones with chlorpyriphos identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that chlorpyriphos is found more frequently in surface, ground or rain water

No

Do the data suggest that chlorpyriphos is found more frequently in large, small or school supplies

No

6.18.2 Detections up to 50% MAV There have been no detections of chlorpyriphos.


6.19 Chlortoluron 6.19.1 Summary information Synonyms 3-(3-chloro-p-tolyl)-1,1-dimethyl urea or

chlorotoluron



50% MAV 0.02 mg/L





Number of community drinking-water zones with chlortoluron identified at > 50% MAV 0

Population served by community drinking-water zones with chlortoluron identified at greater than 50% MAV

0

Population served by community drinking-water zones with chlortoluron identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that chlortoluron is found more frequently in surface, ground or rain water

N/A

Do the data suggest that chlortoluron is found more frequently in large, small or school supplies

N/A

Comment Chlortoluron has not been assessed.


6.20 Cyanazine 6.20.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.00035 mg/L

Remarks (from DWSNZ:2000) No




Number of community drinking-water zones with cyanazine identified at > 50% MAV 0

Population served by community drinking-water zones with cyanazine identified at greater than 50% MAV

0

Population served by community drinking-water zones with cyanazine identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that cyanazine is found more frequently in surface, ground or rain water

N/A

Do the data suggest that cyanazine is found more frequently in large, small or school supplies

N/A

Comment Cyanazine has not been assessed.


6.21 2,4-D 6.21.1 Summary information Synonyms 2,4-dichlorophenoxy acid or

dichlorophenoxyacetic acid



50% MAV 0.02 mg/L





Number of community drinking-water zones with 2,4-D identified at > 50% MAV 0

Population served by community drinking-water zones with 2,4-D identified at greater than 50% MAV

0

Population served by community drinking-water zones with 2,4-D identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 2,4-D is found more frequently in surface, ground or rain water No

Do the data suggest that 2,4-D is found more frequently in large, small or school supplies

No

6.21.2 Detections up to 50% MAV There have been no detections of 2,4-D.


6.22 2,4-DB 6.22.1 Summary information Synonyms 4-(2,4-dichlorophenoxy) butanoic acid or

dichlorophenoxybutyric acid



50% MAV 0.05 mg/L





Number of community drinking-water zones with 2,4-DB identified at > 50% MAV 0

Population served by community drinking-water zones with 2,4-DB identified at greater than 50% MAV

0

Population served by community drinking-water zones with 2,4-DB identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 2,4-DB is found more frequently in surface, ground or rain water

No

Do the data suggest that 2,4-DB is found more frequently in large, small or school supplies

No

6.22.2 Detections up to 50% MAV There have been no detections of 2,4-DB.


6.23 DDT + isomers 6.23.1 Summary information Synonyms 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane



50% MAV 0.001 mg/L





Number of community drinking-water zones with DDT + isomers identified at > 50% MAV

0

Population served by community drinking-water zones with DDT + isomers identified at greater than 50% MAV

0

Population served by community drinking-water zones with DDT + isomers identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that DDT + isomers is found more frequently in surface, ground or rain water

No

Do the data suggest that DDT + isomers is found more frequently in large, small or school supplies

No

6.23.2 Detections up to 50% MAV There have been no detections of DDT.


6.24 Diazinon 6.24.1 Summary information Synonyms O,O-diethyl O-2-isopropyl-6-

methylpyridimidin-4-yl phosphorothioate



50% MAV 0.005 mg/L





Number of community drinking-water zones with diazinon identified at > 50% MAV 0

Population served by community drinking-water zones with diazinon identified at greater than 50% MAV

0

Population served by community drinking-water zones with diazinon identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd - nd


Do the data suggest that diazinon is found more frequently in surface, ground or rain water

No

Do the data suggest that diazinon is found more frequently in large, small or school supplies

No

6.24.2 Detections up to 50% MAV There have been no detections of diazinon.


6.25 1,2-Dibromo-3-chloropropane 6.25.1 Summary information Synonyms 3-chloro-1,2 dibromopropane



50% MAV 0.0005 mg/L





Number of community drinking-water zones with 1,2-dibromo-3-chloropropane identified at > 50% MAV

0

Population served by community drinking-water zones with 1,2-dibromo-3-chloropropane identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,2-dibromo-3-chloropropane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,2-dibromo-3-chloropropane is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,2-dibromo-3-chloropropane is found more frequently in large, small or school supplies

No

6.25.2 Detections up to 50% MAV There have been no detections of 2-dibromo-3-chloropropane.


6.26 1,2-Dichloropropane 6.26.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.01 mg/L





Number of community drinking-water zones with 1,2-dichloropropane identified at > 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloropropane identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloropropane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,2-dichloropropane is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,2-dichloropropane is found more frequently in large, small or school supplies

No

6.26.2 Detections up to 50% MAV There have been no detections of 1,2-dichloropropane.


6.27 1,3-Dichloropropene 6.27.1 Summary information Synonyms dichloro-1,3-propene



50% MAV 0.01 mg/L





Number of community drinking-water zones with 1,3-dichloropropene identified at > 50% MAV

0

Population served by community drinking-water zones with 1,3-dichloropropene identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,3-dichloropropene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,3-dichloropropene is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,3-dichloropropene is found more frequently in large, small or school supplies

No

6.27.2 Detections up to 50% MAV There have been no detections of 1,3-dichloropropane.


6.28 Dichlorprop 6.28.1 Summary information Synonyms 2-(2,4-dichlorophenoxy) propionic acid



50% MAV 0.05 mg/L





Number of community drinking-water zones with dichlorprop identified at > 50% MAV 0

Population served by community drinking-water zones with dichlorprop identified at greater than 50% MAV

0

Population served by community drinking-water zones with dichlorprop identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that dichlorprop is found more frequently in surface, ground or rain water

No

Do the data suggest that dichlorprop is found more frequently in large, small or school supplies

No

6.28.2 Detections up to 50% MAV There have been no detections of dichlorprop.


6.29 Diquat 6.29.1 Summary information Synonyms 9,10-dihydro-8a,10a-diazoniaphenanthrene;

6,7-dihydrodipyrido-(1,2- a:2’,1’c) pyrazine-5,8-di-ium; 1,1’-ethylene-2,2’-bipyridyldiylium



50% MAV 0.005 mg/L





Number of community drinking-water zones with diquat identified at > 50% MAV 0

Population served by community drinking-water zones with diquat identified at greater than 50% MAV

0

Population served by community drinking-water zones with diquat identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that diquat is found more frequently in surface, ground or rain water N/A

Do the data suggest that diquat is found more frequently in large, small or school supplies

N/A

Comment Diquat has not been assessed.


6.30 Diuron 6.30.1 Summary information Synonyms 3-(3,4-dichlorophenyl)-1, 1-dimethylurea



50% MAV 0.01 mg/L





Number of community drinking-water zones with diuron identified at > 50% MAV 0

Population served by community drinking-water zones with diuron identified at greater than 50% MAV

0

Population served by community drinking-water zones with diuron identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that diuron is found more frequently in surface, ground or rain water N/A

Do the data suggest that diuron is found more frequently in large, small or school supplies

N/A

Comment Diuron has not been assessed.


6.31 Fenoprop 6.31.1 Summary information Synonyms 2-(2,4,5-trichlorophenoxy) propionic acid or

silvex



50% MAV 0.005 mg/L





Number of community drinking-water zones with fenoprop identified at > 50% MAV 0

Population served by community drinking-water zones with fenoprop identified at greater than 50% MAV

0

Population served by community drinking-water zones with fenoprop identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that fenoprop is found more frequently in surface, ground or rain water

No

Do the data suggest that fenoprop is found more frequently in large, small or school supplies

No

6.31.2 Detections up to 50% MAV There have been no detections of fenoprop.


6.32 Heptachlor and heptachlor epoxide 6.32.1 Summary information Synonyms 1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-

4,7-methanoindene



50% MAV 0.00002 mg/L





Number of community drinking-water zones with heptachlor and heptachlor epoxide identified at > 50% MAV

0

Population served by community drinking-water zones with heptachlor and heptachlor epoxide identified at greater than 50% MAV

0

Population served by community drinking-water zones with heptachlor and heptachlor epoxide identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that heptachlor and heptachlor epoxide is found more frequently in surface, ground or rain water

No

Do the data suggest that heptachlor and heptachlor epoxide is found more frequently in large, small or school supplies

No

6.32.2 Detections up to 50% MAV There have been no detections of heptachlor or heptachlor epoxide.


6.33 Hexachlorobenzene 6.33.1 Summary information Synonyms Hexachlorobenzene or perchlorobenzene



50% MAV 0.0005 mg/L





Number of community drinking-water zones with hexachlorobenzene identified at > 50% MAV

0

Population served by community drinking-water zones with hexachlorobenzene identified at greater than 50% MAV

0

Population served by community drinking-water zones with hexachlorobenzene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that hexachlorobenzene is found more frequently in surface, ground or rain water

No

Do the data suggest that hexachlorobenzene is found more frequently in large, small or school supplies

No

6.33.2 Detections up to 50% MAV There have been no detections of hexachlorobenzene.


6.34 Hexazinone 6.34.1 Summary information Synonyms 3-cyclohexyl-6-dimethylamino-1-methyl-

1,3,5-triazine



50% MAV 0.2 mg/L





Number of community drinking-water zones with hexazinone identified at > 50% MAV 0

Population served by community drinking-water zones with hexazinone identified at greater than 50% MAV

0

Population served by community drinking-water zones with hexazinone identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that hexazinone is found more frequently in surface, ground or rain water

N/A

Do the data suggest that hexazinone is found more frequently in large, small or school supplies

N/A

Comment Hexazinone has not been assessed.


6.35 Isoproturon 6.35.1 Summary information Synonyms 3-(4-isopropylphenyl)-1,1-dimethyl urea



50% MAV 0.005 mg/L





Number of community drinking-water zones with isoproturon identified at > 50% MAV 0

Population served by community drinking-water zones with isoproturon identified at greater than 50% MAV

0

Population served by community drinking-water zones with isoproturon identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that isoproturon is found more frequently in surface, ground or rain water

N/A

Do the data suggest that isoproturon is found more frequently in large, small or school supplies

N/A

Comment Isoproturon has not been assessed.


6.36 Lindane 6.36.1 Summary information Synonyms Hexachlorocyclohexane or gamma benzene

hexachloride



50% MAV 0.001 mg/L





Number of community drinking-water zones with lindane identified at > 50% MAV 0

Population served by community drinking-water zones with lindane identified at greater than 50% MAV

0

Population served by community drinking-water zones with lindane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that lindane is found more frequently in surface, ground or rain water

No

Do the data suggest that lindane is found more frequently in large, small or school supplies

No

6.36.2 Detections up to 50% MAV There have been no detections of lindane in samples taken for the P2 Programme. Lindane has been tentatively identified in a school supply sampled as a result of a contamination issue identified through P2 Programme sampling. The lindane results were below the limit of detection and thus a lower level of statistical confidence is attached to the results.


6.37 MCPA 6.37.1 Summary information Synonyms 4-chloro-2- methylphenoxyethanoic acid or 4-

chloro-o-toloxyacetic acid



50% MAV 0.001 mg/L





Number of community drinking-water zones with MCPA identified at > 50% MAV 0

Population served by community drinking-water zones with MCPA identified at greater than 50% MAV

0

Population served by community drinking-water zones with MCPA identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that MCPA is found more frequently in surface, ground or rain water

No

Do the data suggest that MCPA is found more frequently in large, small or school supplies

No

6.37.2 Detections up to 50% MAV There have been no detections of MCPA.


6.38 Mecoprop 6.38.1 Summary information Synonyms 2-(4-chloro-o-tolyloxy) propionic acid



50% MAV 0.005 mg/L





Number of community drinking-water zones with mecoprop identified at > 50% MAV 0

Population served by community drinking-water zones with mecoprop identified at greater than 50% MAV

0

Population served by community drinking-water zones with mecoprop identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that mecoprop is found more frequently in surface, ground or rain water

No

Do the data suggest that mecoprop is found more frequently in large, small or school supplies

No

6.38.2 Detections up to 50% MAV There have been no detections of mecoprop.


6.39 Metalaxyl 6.39.1 Summary information Synonyms methyl N-(methoxyacetyl)- N-2,6-xylyl)-DL-

alaninate



50% MAV 0.05 mg/L





Number of community drinking-water zones with metalaxyl identified at > 50% MAV 0

Population served by community drinking-water zones with metalaxyl identified at greater than 50% MAV

0

Population served by community drinking-water zones with metalaxyl identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that metalaxyl is found more frequently in surface, ground or rain water

N/A

Do the data suggest that metalaxyl is found more frequently in large, small or school supplies

N/A

Comment Metalaxyl has not been assessed.


6.40 Methoxychlor 6.40.1 Summary information Synonyms 1,1,1-trichloro-2,2-bis (4-

methoxyphenyl)ethane



50% MAV 0.01 mg/L





Number of community drinking-water zones with methoxychlor identified at > 50% MAV

0

Population served by community drinking-water zones with methoxychlor identified at greater than 50% MAV

0

Population served by community drinking-water zones with methoxychlor identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that methoxychlor is found more frequently in surface, ground or rain water

No

Do the data suggest that methoxychlor is found more frequently in large, small or school supplies

No

6.40.2 Detections up to 50% MAV There have been no detections of methoxychlor.


6.41 Metolachlor 6.41.1 Summary information Synonyms 2-chloro-6'-ethyl-N-(2-methoxy-1-

methylethyl) acet-o-toluidide



50% MAV 0.005 mg/L





Number of community drinking-water zones with metolachlor identified at > 50% MAV 0

Population served by community drinking-water zones with metolachlor identified at greater than 50% MAV

0

Population served by community drinking-water zones with metolachlor identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that metolachlor is found more frequently in surface, ground or rain water

No

Do the data suggest that metolachlor is found more frequently in large, small or school supplies

No

6.41.2 Detections up to 50% MAV There have been no detections of metolachlor.


6.42 Metribuzin 6.42.1 Summary information Synonyms 4-amino-6- tert-butyl-3-(methylthio)-1,2,4-

triazin-5-one



50% MAV 0.035 mg/L





Number of community drinking-water zones with metribuzin identified at > 50% MAV 0

Population served by community drinking-water zones with metribuzin identified at greater than 50% MAV

0

Population served by community drinking-water zones with metribuzin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that metribuzin is found more frequently in surface, ground or rain water

No

Do the data suggest that metribuzin is found more frequently in large, small or school supplies

No

Comment Metribuzin has not been assessed.


6.43 Molinate 6.43.1 Summary information Synonyms S-ethyl-N,N-hexamethylenethiocarbamate



50% MAV 0.0035 mg/L





Number of community drinking-water zones with molinate identified at > 50% MAV 0

Population served by community drinking-water zones with molinate identified at greater than 50% MAV

0

Population served by community drinking-water zones with molinate identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that molinate is found more frequently in surface, ground or rain water

No

Do the data suggest that molinate is found more frequently in large, small or school supplies

No

6.43.2 Detections up to 50% MAV There have been no detections of molinate.


6.44 Oryzalin 6.44.1 Summary information Synonyms 4-(dipropylamino)-3,5-

dinitrobenzenesulphonamide



50% MAV 0.2 mg/L





Number of community drinking-water zones with oryzalin identified at > 50% MAV 0

Population served by community drinking-water zones with oryzalin identified at greater than 50% MAV

0

Population served by community drinking-water zones with oryzalin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that oryzalin is found more frequently in surface, ground or rain water

No

Do the data suggest that oryzalin is found more frequently in large, small or school supplies

No

Comment Oryzalin has not been assessed.


6.45 Oxadiazon 6.45.1 Summary information Synonyms 3-(2,4-dichloro-5-(1-methylethoxy)phenyl)-5-

(1,2,dimethylethyl)-1,3,4-oxydiazol-2-(3H)-one



50% MAV 0.1 mg/L





Number of community drinking-water zones with oxadiazon identified at > 50% MAV 0

Population served by community drinking-water zones with oxadiazon identified at greater than 50% MAV

0

Population served by community drinking-water zones with oxadiazon identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that oxadiazon is found more frequently in surface, ground or rain water

N/A

Do the data suggest that oxadiazon is found more frequently in large, small or school supplies

N/A

Comment Oxadiazon has not been assessed.


6.46 Pendimethalin 6.46.1 Summary information Synonyms N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine



50% MAV 0.01 mg/L





Number of community drinking-water zones with pendimethalin identified at > 50% MAV

0

Population served by community drinking-water zones with pendimethalin identified at greater than 50% MAV

0

Population served by community drinking-water zones with pendimethalin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that pendimethalin is found more frequently in surface, ground or rain water

No

Do the data suggest that pendimethalin is found more frequently in large, small or school supplies

No

6.46.2 Detections up to 50% MAV There have been no detections of pendimethalin.


6.47 Pentachlorophenol 6.47.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.005 mg/L





Number of community drinking-water zones with pentachlorophenol identified at > 50% MAV

0

Population served by community drinking-water zones with pentachlorophenol identified at greater than 50% MAV

0

Population served by community drinking-water zones with pentachlorophenol identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that pentachlorophenol is found more frequently in surface, ground or rain water

No

Do the data suggest that pentachlorophenol is found more frequently in large, small or school supplies

No

6.47.2 Detections up to 50% MAV There have been no detections of pentachlorophenol.


6.48 Permethrin 6.48.1 Summary information Synonyms 3-phenoxybenzyl (1RS)-cis,trans-3-(2,2-

dichlorovinyl) -2,2-dimethyl cyclopropane carboxylate

Isomers cis- and trans-


50% MAV 0.01 mg/L





Number of community drinking-water zones with permethrin identified at > 50% MAV 0

Population served by community drinking-water zones with permethrin identified at greater than 50% MAV

0

Population served by community drinking-water zones with permethrin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that permethrin is found more frequently in surface, ground or rain water

No

Do the data suggest that permethrin is found more frequently in large, small or school supplies

No

6.48.2 Detections up to 50% MAV There have been no detections of permethrin.


6.49 Picloram 6.49.1 Summary information Synonyms 4-amino-3,5,6-trichloro-2-picolinic acid &

grazon



50% MAV 0.1 mg/L





Number of community drinking-water zones with picloram identified at > 50% MAV 0

Population served by community drinking-water zones with picloram identified at greater than 50% MAV

0

Population served by community drinking-water zones with picloram identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that picloram is found more frequently in surface, ground or rain water

N/A

Do the data suggest that picloram is found more frequently in large, small or school supplies

N/A

Comment Picloram has not been assessed.


6.50 Pirimiphos methyl 6.50.1 Summary information Synonyms O-2-diethylamino-6-methyl pyrimidin-4-yl

O,O-dimethylphosphorothioate



50% MAV 0.05 mg/L





Number of community drinking-water zones with pirimiphos methyl identified at > 50% MAV

0

Population served by community drinking-water zones with pirimiphos methyl identified at greater than 50% MAV

0

Population served by community drinking-water zones with pirimiphos methyl identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that pirimiphos methyl is found more frequently in surface, ground or rain water

No

Do the data suggest that pirimiphos methyl is found more frequently in large, small or school supplies

No

6.50.2 Detections up to 50% MAV There have been no detections of pirimiphos methyl.


6.51 Pirimisulfuron methyl 6.51.1 Summary information Synonyms Methyl 2-(((((4,6-bis(difluoromethoxyl)-2-

pyrimidinyl)amino) carbonyl)amino)sulphonyl) benzoic acid



50% MAV 0.45 mg/L





Number of community drinking-water zones with pirimisulfuron methyl identified at > 50% MAV

0

Population served by community drinking-water zones with pirimisulfuron methyl identified at greater than 50% MAV

0

Population served by community drinking-water zones with pirimisulfuron methyl identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that pirimisulfuron methyl is found more frequently in surface, ground or rain water

N/A

Do the data suggest that pirimisulfuron methyl is found more frequently in large, small or school supplies

N/A

Comment Pirimisulfuron methyl has not been assessed.


6.52 Procymidone 6.52.1 Summary information Synonyms N-(3,5-dichlorophenyl)- 1,2-

dimethylcyclopropane- 1,2-dicarboximide or sumisclex



50% MAV 0.35 mg/L





Number of community drinking-water zones with procymidone identified at > 50% MAV

0

Population served by community drinking-water zones with procymidone identified at greater than 50% MAV

0

Population served by community drinking-water zones with procymidone identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that procymidone is found more frequently in surface, ground or rain water

No

Do the data suggest that procymidone is found more frequently in large, small or school supplies

No

6.52.2 Detections up to 50% MAV There have been no detections of procymidone.


6.53 Propanil 6.53.1 Summary information Synonyms N-(3,4-dichlorophenyl) Propionamide



50% MAV 0.01 mg/L





Number of community drinking-water zones with propanil identified at > 50% MAV 0

Population served by community drinking-water zones with propanil identified at greater than 50% MAV

0

Population served by community drinking-water zones with propanil identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that propanil is found more frequently in surface, ground or rain water

No

Do the data suggest that propanil is found more frequently in large, small or school supplies

No

6.53.2 Detections up to 50% MAV There have been no detections of propanil.


6.54 Propazine 6.54.1 Summary information Synonyms 2,4-bis(isopropylamino)-6-chloro-s-triazine



50% MAV 0.035 mg/L





Number of community drinking-water zones with propazine identified at > 50% MAV 0

Population served by community drinking-water zones with propazine identified at greater than 50% MAV

0

Population served by community drinking-water zones with propazine identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that propazine is found more frequently in surface, ground or rain water

N/A

Do the data suggest that propazine is found more frequently in large, small or school supplies

N/A

Comment Propazine has not been assessed.


6.55 Pyridate 6.55.1 Summary information Synonyms 6-chloro-3-phenylpyridazin -4-yl-S-octyl

thiocarbonate



50% MAV 0.05 mg/L





Number of community drinking-water zones with pyridate identified at > 50% MAV 0

Population served by community drinking-water zones with pyridate identified at greater than 50% MAV

0

Population served by community drinking-water zones with pyridate identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that pyridate is found more frequently in surface, ground or rain water

N/A

Do the data suggest that pyridate is found more frequently in large, small or school supplies

N/A

Comment Pyridate has not been assessed.


6.56 Simazine 6.56.1 Summary information Synonyms 6-chloro-N,N’-dimethyl-1,3,5-triazine-2,4-

diamine



50% MAV 0.001 mg/L





Number of community drinking-water zones with simazine identified at > 50% MAV 0

Population served by community drinking-water zones with simazine identified at greater than 50% MAV

0

Population served by community drinking-water zones with simazine identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that simazine is found more frequently in surface, ground or rain water

No

Do the data suggest that simazine is found more frequently in large, small or school supplies

No

6.56.2 Detections up to 50% MAV Simazine has been detected in 1 zone (0.1% of those assessed) at a concentration of 0.0002 mg/L (10% of MAV). 6.56.3 Supporting information Summarized results for simazine are presented for each Public Health Unit in Appendix 3.2.


6.57 2,4,5-T 6.57.1 Summary information Synonyms 2,4,5-trichlorophenoxyethanoic acid or

trichlorophenoxyacetic acid



50% MAV 0.005 mg/L





Number of community drinking-water zones with 2,4,5-T identified at > 50% MAV 0

Population served by community drinking-water zones with 2,4,5-T identified at greater than 50% MAV

0

Population served by community drinking-water zones with 2,4,5-T identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 2,4,5-T is found more frequently in surface, ground or rain water

No

Do the data suggest that 2,4,5-T is found more frequently in large, small or school supplies

No

6.57.2 Detections up to 50% MAV 2,4,5-T has been detected in 1 zone (0.1% of those assessed) at a concentration of 0.0002 mg/L (2% MAV). 6.57.3 Supporting information Summarized results for 2,4,5-T are presented for each Public Health Unit in Appendix 3.3.


6.58 Terbuthylazine 6.58.1 Summary information Synonyms 2-tert-butylamino-4-chloro-6-ethylamino-

1,3,5-triazine



50% MAV 0.004 mg/L





Number of community drinking-water zones with terbuthylazine identified at > 50% MAV

0

Population served by community drinking-water zones with terbuthylazine identified at greater than 50% MAV

0

Population served by community drinking-water zones with terbuthylazine identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that terbuthylazine is found more frequently in surface, ground or rain water

No

Do the data suggest that terbuthylazine is found more frequently in large, small or school supplies

No

6.58.2 Detections up to 50% MAV Terbuthylazine has been detected in 2 zones (0.2% of those assessed) at concentrations from 0.0002 – 0.002 mg/L (2.5 – 25% MAV). 6.58.3 Supporting information Summarized results for terbuthylazine are presented for each Public Health Unit in Appendix 3.4.


6.59 Thiabendazole 6.59.1 Summary information Synonyms 2-(thiazol-4-yl)benzimidazole



50% MAV 0.2 mg/L





Number of community drinking-water zones with thiabendazole identified at > 50% MAV

0

Population served by community drinking-water zones with thiabendazole identified at greater than 50% MAV

0

Population served by community drinking-water zones with thiabendazole identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that thiabendazole is found more frequently in surface, ground or rain water

N/A

Do the data suggest that thiabendazole is found more frequently in large, small or school supplies

N/A

Comment Thiabendazole has not been assessed.


6.60 Triclopyr 6.60.2 Summary information Synonyms 3,5,6-trichloro-2- pyridyloxyethanoic acid or

3,5,6-trichloro-2-pyridyloxyacetic acid



50% MAV 0.05 mg/L





Number of community drinking-water zones with triclopyr identified at > 50% MAV 0

Population served by community drinking-water zones with triclopyr identified at greater than 50% MAV

0

Population served by community drinking-water zones with triclopyr identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that triclopyr is found more frequently in surface, ground or rain water

No

Do the data suggest that triclopyr is found more frequently in large, small or school supplies

No

6.60.2 Detections up to 50% MAV Triclopyr has been detected in 2 zones (0.2% of those assessed) at concentrations of 0.0001 and 0.0006 mg/L (0.1 and 0.6% of MAV). 6.60.3 Supporting information Summarized results for triclopyr are presented for each Public Health Unit in Appendix 3.5.


6.61 Trifluralin 6.61.1 Summary information Synonyms 2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)

benzenamine



50% MAV 0.015 mg/L





Number of community drinking-water zones with trifluralin identified at > 50% MAV 0

Population served by community drinking-water zones with trifluralin identified at greater than 50% MAV

0

Population served by community drinking-water zones with trifluralin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that trifluralin is found more frequently in surface, ground or rain water

No

Do the data suggest that trifluralin is found more frequently in large, small or school supplies

No

6.61.2 Detections up to 50% MAV There have been no detections of trifluralin.


6.62 1080 6.62.1 Summary information Synonyms sodium fluoroethanoate sodium fluoroacetate,

or sodium monofluoroacetate



50% MAV 0.00175 mg/L



Limit of detection for samples taken as part of the P2 Programme 0.0001

Number of community drinking-water zones with 1080 identified at > 50% MAV 0

Population served by community drinking-water zones with 1080 identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1080 identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1080 is found more frequently in surface, ground or rain water N/A

Do the data suggest that 1080 is found more frequently in large, small or school supplies N/A 6.62.2 Detections up to 50% MAV There have been no detections of 1080.


CHAPTER 7: ALGAL TOXINS 7.1 Introduction This chapter reports on detections of algal toxins in New Zealand’s community drinking-water supplies. Algal toxins are toxic chemicals produced within algal cells and released into water. As well as their capacity to be toxic to humans, these chemicals can also adversely affect the taste and odour of a water supply. Eight algal toxins are allocated Maximum Acceptable Values (MAVs) in Table 14.3 of the Drinking-Water Standards for New Zealand:2000 (DWSNZ:2000) (MoH 2000a). These are detailed in Table 7.1. Table 7.1 Algal toxins for which MAVs have been allocated

Toxin MAV mg/L

50% MAV mg/L

Remarks from DWSNZ:2000

Assessed in the P2 Programme?

Anatoxin-a (as STX-eq) 0.003 0.0015 PMAV No Anatoxin-a (S) 0.001 0.0005 PMAV No Cylindrospermopsin 0.003 0.0015 PMAV No Homoanatoxin-a 0.001 0.0005 PMAV No LPS endoxins 0.003 0.0015 PMAV No Microcystins 0.001 0.0005 PMAV No Nodularin 0.001 0.0005 PMAV No Saxitoxins 0.001 0.0005 PMAV No PMAV = Provisional Maximum Acceptable Value Phase 1 of the P2 Programme covered the period 1995 – 2000. During this time, the version of drinking water standards in use was the Drinking-Water Standards for New Zealand:1995 (DWSNZ:1995) (MoH 1995). Algal toxins have not been assessed because at the time the data was collected the only MAV relating to them referred to the micro-organisms themselves (MAV = no toxic algae present in 10ml of sample). 7.2 Future assessment of algal toxins There have been no nationwide programmes to assess algal toxins in community drinking-water supplies. Should algal toxins be assessed through a nationwide process, particular attention would need to be given to the seasonal occurrence of algal blooms, and consequential seasonal variability of algal toxin concentrations. Treatment processes can reduce or exacerbate toxin levels and are also of relevance to any identification process. Not only does this complicate sampling to identify toxins, but any monitoring prescribed in the DWSNZ:2000 that results from identification of algal toxins at greater than 50% MAVs would need to reflect this variability. Because testing for algal toxins is relatively costly, it is suggested any identification process should include investigation of density and species within algal blooms, prior to any water analysis being conducted.


CHAPTER 8: OTHER ORGANICS 8.1 Introduction This chapter reports on detections of organic compounds other than disinfection by-products (Chapter 5), pesticides (Chapter 6) and algal toxins (Chapter 7) in New Zealand’s community drinking-water supplies. These remaining organic chemicals, not covered in previous chapters, are termed ‘other organics’. The ‘other organics’ covered in this report are limited to those listed in Table 14.3 of the Drinking-Water Standards for New Zealand:2000 (DWSNZ:2000) (MoH 2000a). Thirty ‘other organics’ are allocated Maximum Acceptable Values (MAVs) or Provisional Maximum Acceptable Values (PMAVs) in Table 14.3 of the DWSNZ:2000 (MoH 2000a). Additionally, PAHs are identified as a group in Table 14.7 of the DWSNZ:2000 as total PAH mixture, making a total of thirty-one determinands. Twenty seven of these chemicals have been assessed, and the results of the assessments are reported in this chapter. Phase 1 of the P2 Programme covered the period 1995 – 2000. During this time, the version of drinking water standards in use was the Drinking-Water Standards for New Zealand:1995 (DWSNZ:1995) (MoH 1995a). The following changes are seen in the DWSNZ:2000 New organic determinands with MAVs: Fluoranthene

PAHs (polycyclic aromatic hydrocarbons)

Altered MAVs: EDTA from 0.2 mg/L to 0.7 mg/L.

The 2000 version of the Standards introduced a MAV for fluoranthene. Fluoranthene has been assessed, and results have been included in this report. Four organic compounds have not been assessed. EDTA, epichlorohydrin and nitrilotriacetic acid were not assessed because there were no analytical methods available for them. The determinand newly added to the DWSNZ:2000 - total PAH mixture - has not been assessed (although fluoranthene, and a number of other PAHs have been assessed). A number of the determinands listed in the DWSNZ:2000 have the acronym ATO listed as a remark. This indicates that concentrations of the substance at or below the MAV may affect the appearance, taste or odour of the water. The potential for appearance, taste or odour problems for the determinands detected is noted. 8.2 Origins of the analytical data 8.2.1 P2 Programme: Baseline sampling Organic compounds are not included in the Baseline sampling round of the P2 Programme.


8.2.2 P2 Programme: M1 and M2 sampling The first and second monitoring rounds (M1 and M2), which follow the Baseline sampling round for each zone, are targeted towards those determinands that have been selected as having the potential to be present in the zone at health significant concentrations. Results from the Baseline sampling, along with information collected through questionnaires, were used to select determinands to include in the targeted sampling. If selected, organic compounds were included in two rounds of sampling – the M1 and M2 round. 8.3 Summary of results The summary table that follows is a compilation of results collected for each organic compound covered in this chapter. Further details relating to each determinand can be found by referring to the page dedicated to it.


Table 8.1 Summary table for ‘other organics’ = Yes = No Name MAV

mg/L Assessed Detected > 50%

MAV Transgression Appearance,

taste and odour

LoD mg/L

LoD as a % of the

MAV Acrylamide 0.0005 1 zone 0.0001 20% Benzene 0.01 4 zones 0.0005 5% Benzo(a)pyrene 0.0007 0.0001 14% Carbon tetrachloride 0.002 0.0005 25% Di(2-ethylhexyl)adipate 0.1 0.002 2% Di(2-ethylhexyl) phthalate

0.009 6 zones 1 zone

0.002 22%

1,2-Dichlorobenzene 1 ATO 0.0005 0.05% 1,4-Dichlorobenzene 0.4 1 zone ATO 0.0005 0.1% 1,2-Dichloroethane 0.03 0.0005 1.7% 1,1-Dichloroethene 0.03 0.0005 1.7% 1,2-Dichloroethene 0.06 0.0005 0.8% Dichloromethane 0.02 0.008 40% 1,2-Dichloropropane 0.02 0.0005 2.5% EDTA 0.7 Not


Epichlorohydrin 0.0005 Not assessed

Not assessed

Ethylbenzene 0.3 2 zones ATO 0.0005 0.17% Fluoranthene 0.004 1 zone 0.0002 5% Hexachlorobutadiene 0.0007 0.0005 71% Monochlorobenzene 0.3 ATO 0.0005 0.17% Nitrilotriacetic acid 0.2 Not


Total PAH mixture 0.001 0.0005 1.7% Styrene 0.03 ATO 0.001 2% Tetrachloroethene 0.05 7 zones 0.001 0.125% Toluene 0.8 4 zones ATO 0.00005 2.5% Tributyltin oxide 0.002 0.0005 1.7% Trichlorobenzenes (total)

0.03 ATO 0.001 0.05%

1,1,1-Trichloroethane 2 1 zone 0.001 1.25% Trichloroethene 0.08 1 zone 0.005 2.5% 2,4,6-Trichlorophenol

0.2 ATO 0.001 20%

Vinyl chloride 0.005 0.0005 0.08% Xylenes 0.6 7 zones ATO

8.4 Aromatic hydrocarbons The P2 programme has detected benzene, toluene, ethylbenzene and xylenes in a number of distribution zones. None of these exceed the MAV. These aromatic hydrocarbons are a constituent of gasoline and other petroleum hydrocarbon products. Gasoline is widely used and stored in New Zealand. Furthermore, taps at petrol stations are frequently used as sampling locations because of the ease with which Health Protection Officers can gain access to sampling points. The potential for cross contamination by vapour entering the sample bottle or from use of a contaminated sampling tap, rather than any source water contamination is of note with regards to the results obtained for these compounds. The


locations used to collect samples where aromatic hydrocarbons were identified should be investigated. 8.5 Chlorinated hydrocarbons Chlorinated hydrocarbons are often identified in the literature as groundwater contaminants, and this is a result of their persistence, mobility and widespread industrial use. Four different chlorinated hydrocarbons have been identified in New Zealand’s community drinking-water supplies. None of these exceed 50% MAV. Tetrachloroethene is the most frequently identified chlorinated hydrocarbon having been detected in seven zones at concentrations ranging from 1.6% - 8% MAV. 8.6 Transgressions and detections over fifty percent of the Maximum Acceptable Value (MAV) Twenty-seven ‘other organics’ were assessed in Phase 1 of the P2 Programme. No transgressions of the MAV were detected. Concentrations that exceeded 50% of the MAV were detected for one determinand only – di(2-ethylhexyl)phthalate - in one zone. This zone has a population of 121. None of the remaining twenty-six organic compounds were detected at concentrations greater than 50% of their MAV. 8.7 Detections to 50% MAV Eleven ‘other organics’ have been detected. Detection results are presented in Table 8.2. Table 8.2 Organic determinands (other than disinfection by-products and pesticides)

detected in community drinking-water supplies at less than 50% of their MAVs

Determinand Type of chemical Detections LoD Range of detections

expressed as % of MAV

No. of zones

Population mg/L % of MAV

Acrylamide Acrylic amide 1 500 0.0001 20% 24% Benzene Aromatic hydrocarbon 4 3,300 0.0005 5% 7% - 36%

Di(2-ethylhexyl) phthalate* Plasticiser 5 4,690 0.002 22% 32.2% - 77.8% 1,4-Dichlorobenzene Halogenated aromatic 1 63 0.0005 0.1% 5% - 9%

Ethylbenzene Aromatic hydrocarbon 2 2,100 0.0005 0.17% 0.4% - 0.6% Fluoranthene Polycyclic aromatic hydrocarbon

(PAH) 1 25,800 0.0002 5% 5%

Tetrachloroethene Halogenated alkene 7 16,057 0.001 2% 1.6% - 8% Toluene Aromatic hydrocarbon 4 3,600 0.01 0.125% 0.14% - 2.5%

1,1,1-Trichloroethane Halogenated alkane 1 2,400 0.001 0.05% 0.2% Trichloroethene Halogenated alkene 1 150 0.001 1.25% 2%

Xylenes Aromatic hydrocarbon 7 12,850 0.0005 0.08% 0.2% - 3.7% LoD = Limit of detection of the analytical method (detections may be recorded at lower than the limit of detection if they were analysed at a time when the analytical method was enabling lower LoDs than was usual). MAV = Maximum Acceptable Value * One of the results for Di(2-ethylhexyl)phthalate was greater than 50% MAV


Acrylamide has been detected in one zone. This determinand differs from the other determinands in that it is a contaminant introduced as a result of the addition of treatment plant chemicals (in this case, polyelectrolytes). The origin of the plasticiser - di(2-ethylhexyl) phthalate – detected in five zones and at a concentration that exceeded 50% MAV in one of these - may be plastic pipework. It is considered unlikely that this chemical was present in the source water. High analytical limits of detection are identified in this report as hindering the appropriate assessment of four of the organic compounds covered in this chapter (see Table 8.1). The analytical specifications for the Priority 2 Programme dictate a maximum limit of detection of 20% of the MAV for all chemicals assessed in the Programme. This figure was chosen to enable an adequate margin of confidence to be attached to any Priority 2 classifications (results greater than 50% MAV) that were made from the analytical results generated through the Programme. It could be argued, in the case of man-made chemicals that are found in community drinking-water supplies, that 20% of the MAV indicates a high level of contamination, and that lower levels should warrant action on the part of those who manage land use activities. However, the very low MAVs attached to many of the organic chemicals makes obtaining a limit of detection of 20% MAV problematic with the analytical methods available. 8.8 Geographical distribution There is no relationship between detections of ‘other organics’ and geographical distributions apparent from the small number of detections. 8.9 Source types Because ‘other organics’ were detected in so few zones, it has not been possible to determine any relationship between source type (rain, surface or groundwater) and the detection of pesticides. 8.10 Unassessed zones The small number of detections of ‘other organics’ prohibits any inferences to be made with respect to unassessed zones. Monitoring programmes directed at intensive sampling from different aquifers is likely to provide more useful information for unassessed zones. An example of the reporting of this type of programme is ‘Groundwater contamination by hydrocarbons in Canterbury: A review of monitoring data from April 1988 to June 1999’ by Hayward and Smith, Environment Canterbury. 8.11 Information gaps Three points have been identified as information gaps: 1. The high analytical detection limits for four of the organic compounds. 2. The lack of assessment of EDTA, epichlorohydrin and nitrilotriacetic acid.


3. The lack of assessment of the PAH group as a whole, which has a Provisional Maximum Acceptable Value (PMAV) of 0.001 mg/L for the total PAH mixture listed in Table 14.7 of the DWSNZ:2000.

A study of the characteristics (eg half life, mobility, density) of the organic determinands detected in community drinking-water supplies may provide information of use to those with resource management responsibilities.


8.12 Acrylamide 8.12.1 Summary information Synonyms Propenamide



50% MAV 0.00025 mg/L





Number of community drinking-water zones with acrylamide identified at > 50% MAV 0

Population served by community drinking-water zones with acrylamide identified at greater than 50% MAV

0

Population served by community drinking-water zones with acrylamide identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that acrylamide is found more frequently in surface, ground or rain water

No

Do the data suggest that acrylamide is found more frequently in large, small or school supplies

No

8.12.2 Detections up to 50% MAV Acrylamide was detected in one zone (0.1% of those assessed) at a concentration of 0.00012 mg/L (25% of MAV). 8.12.3 Supporting information Summarised results for acrylamide are presented for each Public Health Unit in Appendix 4.3.


8.13 Benzene 8.13.1 Summary information Synonyms phenyl hydride



50% MAV 0.005 mg/L





Number of community drinking-water zones with benzene identified at > 50% MAV 0

Population served by community drinking-water zones with benzene identified at greater than 50% MAV

0

Population served by community drinking-water zones with benzene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that benzene is found more frequently in surface, ground or rain water

No

Do the data suggest that benzene is found more frequently in large, small or school supplies

No

8.13.2 Detections up to 50% MAV There is a possible issue of contamination of samples that have been collected at petrol service stations (benzene is a significant constituent of gasoline). Benzene was detected in four zones (0.5% of those assessed). The concentration range was 0.0015 – 0.0036 mg/L (>-36%MAV). Also see ethylbenzene, toluene and xylenes. 8.13.3 Supporting information Summarised results for benzene are presented for each Public Health Unit in Appendix 4.3.


8.14 Benzo(a)pyrene 8.14.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.00035 mg/L





Number of community drinking-water zones with benzo(a)pyrene identified at > 50% MAV

0

Population served by community drinking-water zones with benzo(a)pyrene identified at greater than 50% MAV

0

Population served by community drinking-water zones with benzo(a)pyrene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that benzo(a)pyrene is found more frequently in surface, ground or rain water

No

Do the data suggest that benzo(a)pyrene is found more frequently in large, small or school supplies

No

8.14.2 Detections up to 50% MAV There have been no detections of benzo(a)pyrene.


8.15 Carbon tetrachloride 8.15.1 Summary information Synonyms Tetrachloromethane



50% MAV 0.001 mg/L





Number of community drinking-water zones with carbon tetrachloride identified at > 50% MAV

0

Population served by community drinking-water zones with carbon tetrachloride identified at greater than 50% MAV

0

Population served by community drinking-water zones with carbon tetrachloride identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that carbon tetrachloride is found more frequently in surface, ground or rain water

No

Do the data suggest that carbon tetrachloride is found more frequently in large, small or school supplies

No

8.15.2 Detections up to 50% MAV There have been no detections of carbon tetrachloride.


8.16 Di(2-ethylhexyl)adipate 8.16.1 Summary information Synonyms bis(2-ethylhexyl)adipate



50% MAV 0.05 mg/L





Number of community drinking-water zones with di(2-ethylhexyl)adipate identified at > 50% MAV

0

Population served by community drinking-water zones with di(2-ethylhexyl)adipate identified at greater than 50% MAV

0

Population served by community drinking-water zones with di(2-ethylhexyl)adipate identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that di(2-ethylhexyl)adipate is found more frequently in surface, ground or rain water

No

Do the data suggest that di(2-ethylhexyl)adipate is found more frequently in large, small or school supplies

No

8.16.2 Detections up to 50% MAV There have been no detections of di(z-ethylhexyl)adipate.


8.17 Di(2-ethylhexyl) phthalate 8.17.1 Summary information Synonyms bis(2-ethylhexyl) phthalate



50% MAV 0.0045 mg/L





Number of community drinking-water zones with di(2-ethylhexyl) phthalate identified at > 50% MAV

1

Population served by community drinking-water zones with di(2-ethylhexyl) phthalate identified at greater than 50% MAV

121

Population served by community drinking-water zones with di(2-ethylhexyl) phthalate identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that di(2-ethylhexyl) phthalate is found more frequently in surface, ground or rain water

No

Do the data suggest that di(2-ethylhexyl) phthalate is found more frequently in large, small or school supplies

No

8.17.2 Detections up to 50% MAV Di(2-ethylhexyl)phthalate has been detected in five zones (0.7% of those assessed) at a concentration range of 0.0029 – 0.007 mg/L (32.2 – 77.8% of MAV. Di(2-ethylhexyl)phthalate is a plasticizer, and its presence can be associated with plastic tap fittings and pipeware rather than contamination of source water. 8.17.3 Supporting information Summarised results for di(2-ethylhexyl)phthalate are presented for each Public Health Unit in Appendix 4.3.


8.18 1,2-Dichlorobenzene 8.18.1 Summary information Synonyms Orthodichlorobenzene



50% MAV 0.5 mg/L





Number of community drinking-water zones with 1,2-dichlorobenzene identified at > 50% MAV

0

Population served by community drinking-water zones with 1,2-dichlorobenzene identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,2-dichlorobenzene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,2-dichlorobenzene is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,2-dichlorobenzene is found more frequently in large, small or school supplies

No

8.18.2 Detections up to 50% MAV There have been no detections of 1,2-dichlorobenzene.


8.19 1,4-Dichlorobenzene 8.19.1 Summary information Synonyms Paradichlorobenzene



50% MAV 0.2 mg/L





Number of community drinking-water zones with 1,4-dichlorobenzene identified at > 50% MAV

0

Population served by community drinking-water zones with 1,4-dichlorobenzene identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,4-dichlorobenzene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,4-dichlorobenzene is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,4-dichlorobenzene is found more frequently in large, small or school supplies

No

8.19.2 Detections up to 50% MAV 1,4-dichlorobenzene has been detected twice in one zone (0.1% of those assessed) at concentrations of 0.0005 and 0.0009 mg/L (5-9% of MAV). 8.19.3 Supporting information Summarised results for 1,4-dichlorobenzene are presented for each Public Health Unit in Appendix 4.4.


8.20 1,2-Dichloroethane 8.20.1 Summary information Synonyms ethylene dichloride



50% MAV 0.015 mg/L

Remarks (from DWSNZ:2000) for excess lifetime cancer risk of 10-5




Number of community drinking-water zones with 1,2-dichloroethane identified at > 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloroethane identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloroethane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,2-dichloroethane is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,2-dichloroethane is found more frequently in large, small or school supplies

No

8.20.2 Detections up to 50% MAV 1,2-dichloroethane has been detected in one zone (0.1% of those assessed). 8.20.3 Supporting information Summarised results for 1,2-dichloroethane are presented for each Public Health Unit in Appendix 4.5.


8.21 1,1-Dichloroethene 8.21.1 Summary information Synonyms Vinylidene chloride



50% MAV 0.015 mg/L





Number of community drinking-water zones with 1,1-dichloroethene identified at > 50% MAV

0

Population served by community drinking-water zones with 1,1-dichloroethene identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,1-dichloroethene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,1-dichloroethene is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,1-dichloroethene is found more frequently in large, small or school supplies

No

8.21.2 Detections up to 50% MAV There have been no detections of 1,1-dichloroethene.


8.22 1,2-Dichloroethene 8.22.1 Summary information Synonyms ethylene dichloride

Isomers cis and trans


50% MAV 0.03 mg/L





Number of community drinking-water zones with 1,2-dichloroethene identified at > 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloroethene identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloroethene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,2-dichloroethene is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,2-dichloroethene is found more frequently in large, small or school supplies

No

8.22.2 Detections up to 50% MAV There have been no detections of 1,2-dichloroethene.


8.23 Dichloromethane 8.23.1 Summary information Synonyms methylene chloride



50% MAV 0.01 mg/L





Number of community drinking-water zones with dichloromethane identified at > 50% MAV

0

Population served by community drinking-water zones with dichloromethane identified at greater than 50% MAV

0

Population served by community drinking-water zones with dichloromethane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that dichloromethane is found more frequently in surface, ground or rain water

No

Do the data suggest that dichloromethane is found more frequently in large, small or school supplies

No

8.23.2 Detections up to 50% MAV There have been no detections of dichloromethane. The high limit of detection (40% of MAV) is of note. Comments Dichloromethane is also listed within the ‘Disinfection By-products’ chapter.


8.24 1,2-Dichloropropane 8.24.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.01 mg/L

Remarks (from DWSNZ:2000) See 1998 WHO – also listed as pesticide




Number of community drinking-water zones with 1,2-dichloropropane identified at > 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloropropane identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,2-dichloropropane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,2-dichloropropane is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,2-dichloropropane is found more frequently in large, small or school supplies

No

8.24.2 Detections up to 50% MAV There have been no detections of 1,2-dichloropropane. Comments 1,2-dichloropropane is also listed in the ‘Pesticides’ chapter.


8.25 EDTA 8.25.1 Summary information Synonyms Ethylenediamine tetra-acetic acid edetic acid



50% MAV 0.35 mg/L

Remarks (from DWSNZ:2000) WHO

Assessed in the P2 Programme? No: Method development required for this

analyte



Number of community drinking-water zones with EDTA identified at > 50% MAV 0

Population served by community drinking-water zones with EDTA identified at greater than 50% MAV

0

Population served by community drinking-water zones with EDTA identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that EDTA is found more frequently in surface, ground or rain water N/A

Do the data suggest that EDTA is found more frequently in large, small or school supplies

N/A

Comment EDTA was not assessed in Phase 1 of the P2 Programme.


8.26 Epichlorohydrin 8.26.1 Summary information Synonyms 1-chloro-2,3-epoxypropane or chloromethyl

oxirane or chloromethyl ethylene oxide



50% MAV 0.00025 mg/L

Remarks (from DWSNZ:2000) PMAV WHO


analyte



Number of community drinking-water zones with epichlorohydrin identified at > 50% MAV

0

Population served by community drinking-water zones with epichlorohydrin identified at greater than 50% MAV

0

Population served by community drinking-water zones with epichlorohydrin identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that epichlorohydrin is found more frequently in surface, ground or rain water

N/A

Do the data suggest that epichlorohydrin is found more frequently in large, small or school supplies

N/A

Comment Epichlorohydrin was not assessed in Phase 1 of the P2 Programme.


8.27 Ethylbenzene 8.27.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.15 mg/L





Number of community drinking-water zones with ethylbenzene identified at > 50% MAV

0

Population served by community drinking-water zones with ethylbenzene identified at greater than 50% MAV

0

Population served by community drinking-water zones with ethylbenzene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that ethylbenzene is found more frequently in surface, ground or rain water

No

Do the data suggest that ethylbenzene is found more frequently in large, small or school supplies

No

8.27.2 Detections up to 50% MAV Ethylbenzene has been detected in two zones (0.2% of those assessed) at concentrations of 0.0011 and 0.0018 mg/L (0.4 – 0.6% MAV). There is a possible issue of contamination of samples that have been collected at petrol service stations (ethylbenzene is a significant constituent of gasoline). Also see benzene, toluene and xylenes. 8.27.3 Supporting information Summarised results for ethylbenzene are presented for each Public Health Unit in Appendix 4.5.


8.28 Fluoranthene 8.28.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.002 mg/L

Remarks (from DWSNZ:2000) WHO PMAV




Number of community drinking-water zones with fluoranthene identified at > 50% MAV

0

Population served by community drinking-water zones with fluoranthene identified at greater than 50% MAV

0

Population served by community drinking-water zones with fluoranthene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that fluoranthene is found more frequently in surface, ground or rain water

No

Do the data suggest that fluoranthene is found more frequently in large, small or school supplies

No

8.28.2 Detections up to 50% MAV Fluoranthene has been detected in one zone (0.1% of those assessed) at concentrations of 0.0002 mg/L (5% of MAV). 8.28.3 Supporting information Summarised results for fluoranthene are presented for each Public Health Unit in Appendix 4.6.


8.29 Hexachlorobutadiene 8.29.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.00035 mg/L





Number of community drinking-water zones with hexachlorobutadiene identified at > 50% MAV

0

Population served by community drinking-water zones with hexachlorobutadiene identified at greater than 50% MAV

0

Population served by community drinking-water zones with hexachlorobutadiene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that hexachlorobutadiene is found more frequently in surface, ground or rain water

No

Do the data suggest that hexachlorobutadiene is found more frequently in large, small or school supplies

No

8.29.2 Detections up to 50% MAV There have been no detections of hexachlorobutadiene. The high limit of detection (71% of MAV) is of note.


8.30 Monochlorobenzene 8.30.1 Summary information Synonyms chlorobenzene or phenyl chloride



50% MAV 0.15 mg/L





Number of community drinking-water zones with monochlorobenzene identified at > 50% MAV

0

Population served by community drinking-water zones with monochlorobenzene identified at greater than 50% MAV

0

Population served by community drinking-water zones with monochlorobenzene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that monochlorobenzene is found more frequently in surface, ground or rain water

No

Do the data suggest that monochlorobenzene is found more frequently in large, small or school supplies

No

8.30.2 Detections up to 50% MAV There have been no detections of monochlorobenzene.


8.31 Nitrilotriacetic acid 8.31.1 Summary information Synonyms N,N-bis(carboxymethyl) glycine or triglycine



50% MAV 0.1 mg/L



analyte



Number of community drinking-water zones with nitrilotriacetic acid identified at > 50% MAV

0

Population served by community drinking-water zones with nitrilotriacetic acid identified at greater than 50% MAV

0

Population served by community drinking-water zones with nitrilotriacetic acid identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that nitrilotriacetic acid is found more frequently in surface, ground or rain water

N/A

Do the data suggest that nitrilotriacetic acid is found more frequently in large, small or school supplies

N/A

Comment Nitrilotriacetic acid has not been assessed in Phase 1 of the P2 Programme.


8.32 PAHs 8.32.1 Summary information Synonyms Polycyclic aromatic hydrocarbons


Maximum Acceptable Value (MAV) Total PAH mixture: 0.001 mg/L

50% MAV 0.0005 mg/L





Number of community drinking-water zones with nitrilotriacetic acid identified at > 50% MAV

0

Population served by community drinking-water zones with nitrilotriacetic acid identified at greater than 50% MAV

0

Population served by community drinking-water zones with nitrilotriacetic acid identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that nitrilotriacetic acid is found more frequently in surface, ground or rain water

N/A

Do the data suggest that nitrilotriacetic acid is found more frequently in large, small or school supplies

N/A

Comment: A number of PAH’s have been assessed in Phase 1 of the P2 Programme. With the exception of fluoranthene, discussed earlier in this chapter, none have been detected. The limits of detection range from 0.0001 to 0.0002 mg/L.


8.33 Styrene 8.33.1 Summary information Synonyms phenylethene or vinyl benzene



50% MAV 0.015 mg/L





Number of community drinking-water zones with styrene identified at > 50% MAV 0

Population served by community drinking-water zones with styrene identified at greater than 50% MAV

0

Population served by community drinking-water zones with styrene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that styrene is found more frequently in surface, ground or rain water

No

Do the data suggest that styrene is found more frequently in large, small or school supplies

No

8.33.2 Detections up to 50% MAV There have been no detections of styrene.


8.34 Tetrachloroethene 8.34.1 Summary information Synonyms tetrachloroethylene



50% MAV 0.025 mg/L





Number of community drinking-water zones with tetrachloroethene identified at > 50% MAV

0

Population served by community drinking-water zones with tetrachloroethene identified at greater than 50% MAV

0

Population served by community drinking-water zones with tetrachloroethene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that tetrachloroethene is found more frequently in surface, ground or rain water

No

Do the data suggest that tetrachloroethene is found more frequently in large, small or school supplies

No

8.34.2 Detections up to 50% MAV Tetrachloroethene has been detected in seven zones (0.8% of those assessed) at concentrations between 0.005 and 0.004 mg/L (1.6 and 8% of MAV). The very low concentration was recorded in a sample analysed at a time when the analytical method was capable of achieving a lower limit of detection than was standard. 8.34.3 Supporting information Summarised results for tetrachloroethene are presented for each Public Health Unit in Appendix 4.7.


8.35 Toluene 8.35.1 Summary information Synonyms Methylbenzene



50% MAV 0.4 mg/L





Number of community drinking-water zones with toluene identified at > 50% MAV 0

Population served by community drinking-water zones with toluene identified at greater than 50% MAV

0

Population served by community drinking-water zones with toluene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that toluene is found more frequently in surface, ground or rain water

No

Do the data suggest that toluene is found more frequently in large, small or school supplies

No

8.35.2 Detections up to 50% MAV Toluene has been detected in four zones (0.5% of those assessed) at concentrations between 0.0011 and 0.02 mg/L (0.14 – 2.5% of MAV). There is a possible issue of contamination of samples that have been collected at petrol service stations (toluene is a significant constituent of gasoline). Also see benzene, ethylbenzene and xylenes. 8.35.3 Supporting information Summarised results for toluene are presented for each Public Health Unit in Appendix 4.8.


8.36 Tributyltin oxide 8.36.1 Summary information Synonyms None listed in DWSNZ



50% MAV 0.001 mg/L





Number of community drinking-water zones with tributyltin oxide identified at > 50% MAV

0

Population served by community drinking-water zones with tributyltin oxide identified at greater than 50% MAV

0

Population served by community drinking-water zones with tributyltin oxide identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that tributyltin oxide is found more frequently in surface, ground or rain water

No

Do the data suggest that tributyltin oxide is found more frequently in large, small or school supplies

No

8.36.2 Detections up to 50% MAV There have been no detections of tributyltin oxide because no samples have been analysed for it. An analytical technique for tributyltin oxide became available in the 1998/99 Programme Round.


8.37 Trichlorobenzenes (total) 8.37.1 Summary information Synonyms 1,2,3-trichlorobenzene or 1,2,4-

trichlorobenzene or 1,3,5-trichlorobenzene



50% MAV 0.015 mg/L





Number of community drinking-water zones with trichlorobenzenes (total) identified at > 50% MAV

0

Population served by community drinking-water zones with trichlorobenzenes (total) identified at greater than 50% MAV

0

Population served by community drinking-water zones with trichlorobenzenes (total) identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that trichlorobenzenes (total) is found more frequently in surface, ground or rain water

No

Do the data suggest that trichlorobenzenes (total) is found more frequently in large, small or school supplies

No

8.37.2 Detections up to 50% MAV There have been no detections of trichlorobenzenes (total).


8.38 1,1,1-Trichloroethane 8.38.1 Summary information Synonyms methylchloroform, or chlorothene



50% MAV 1 mg/L





Number of community drinking-water zones with 1,1,1-trichloroethane identified at > 50% MAV

0

Population served by community drinking-water zones with 1,1,1-trichloroethane identified at greater than 50% MAV

0

Population served by community drinking-water zones with 1,1,1-trichloroethane identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 1,1,1-trichloroethane is found more frequently in surface, ground or rain water

No

Do the data suggest that 1,1,1-trichloroethane is found more frequently in large, small or school supplies

No

8.38.2 Detections up to 50% MAV 1,1,1-trichloroethane has been detected in one zone (0.1% of those assessed) at concentration of 0.003 mg/L (0.2% MAV). 8.38.3 Supporting information Summarised results for 1,1,1-trichloroethane are presented for each Public Health Unit in Appendix 4.9.


8.39 Trichloroethene 8.39.1 Summary information Synonyms Trichloroethylene



50% MAV 0.04 mg/L





Number of community drinking-water zones with trichloroethene identified at > 50% MAV

0

Population served by community drinking-water zones with trichloroethene identified at greater than 50% MAV

0

Population served by community drinking-water zones with trichloroethene identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that trichloroethene is found more frequently in surface, ground or rain water

No

Do the data suggest that trichloroethene is found more frequently in large, small or school supplies

No

8.39.2 Detections up to 50% MAV Trichloroethene has been detected twice in one zone (0.1% of those assessed) at concentrations of 0.0016 and 0.0017 mg/L (2.0 and 2.1% of MAV). 8.39.3 Supporting information Summarised results for trichloroethene are presented for each Public Health Unit in Appendix 4.10.


8.40 2,4,6-Trichlorophenol 8.40.1 Summary information Synonyms Trihalomethane



50% MAV 0.1 mg/L

Remarks (from DWSNZ:2000) For excess lifetime cancer risk of 10-5 , ATO




Number of community drinking-water zones with 2,4,6-trichlorophenol identified at > 50% MAV

0

Population served by community drinking-water zones with 2,4,6-trichlorophenol identified at greater than 50% MAV

0

Population served by community drinking-water zones with 2,4,6-trichlorophenol identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that 2,4,6-trichlorophenol is found more frequently in surface, ground or rain water

No

Do the data suggest that 2,4,6-trichlorophenol is found more frequently in large, small or school supplies

No

8.40.2 Detections up to 50% MAV There have been no detections of 2,4,6-trichlorophenol.


8.41 Vinyl chloride 8.41.1 Summary information Synonyms chloroethene



50% MAV 0.0025 mg/L

Remarks (from DWSNZ:2000) for excess lifetime cancer risk of 10-5




Number of community drinking-water zones with vinyl chloride identified at > 50% MAV

0

Population served by community drinking-water zones with vinyl chloride identified at greater than 50% MAV

0

Population served by community drinking-water zones with vinyl chloride identified at greater than MAV, i.e. health significant concentrations

0



Do the data suggest that vinyl chloride is found more frequently in surface, ground or rain water

No

Do the data suggest that vinyl chloride is found more frequently in large, small or school supplies

No

8.41.2 Detections up to 50% MAV There have been no detections of vinyl chloride.


8.42 Xylenes 8.42.1 Summary information Synonyms 1,2-dimethylbenzene or 1,3-dimethylbenzene

or 1,4-dimethylbenzene or orthodimethylbenzene or metadimethylbenzene or paradimethylbenzene



50% MAV 0.3 mg/L





Number of community drinking-water zones with xylenes identified at > 50% MAV 0

Population served by community drinking-water zones with xylenes identified at greater than 50% MAV

0

Population served by community drinking-water zones with xylenes identified at greater than MAV, i.e. health significant concentrations

0

Range of P2 Programme results nd – 0.022 mg/L (m&p xylene), nd – 0.0099 mg/L (σ-xylene)

Median of P2 Programme results Nd

Do the data suggest that xylenes is found more frequently in surface, ground or rain water

No

Do the data suggest that xylenes is found more frequently in large, small or school supplies

No

8.42.2 Detections up to 50% MAV m&p-xylenes have been detected in four zones (0.5% of those assessed) at concentrations ranging from 0.0012 – 0.022 mg/L (0.2 – 3.7% MAV), σ -xylenes have been detected in three zones (0.4% of those assessed) at concentrations ranging from 0.0006 – 0.0099 mg/L (0.1 – 1.7% MAV) There is a possible issue of contamination of samples that have been collected at petrol service stations (xylenes are a significant constituent of gasoline). Also see benzene, ethylbenzene and toluene. 8.42.3 Supporting information Summarised results for σ-xylene are presented for each Public Health Unit in Appendix 4.11, and for m+p-xylene in Appendix 4.12.


REFERENCES Board of Health 1984: Drinking-Water Standards for New Zealand. A report prepared for the Board of Health by the Department of Health. Close, 1996: Survey of Pesticides in New Zealand Groundwaters, 1994. In: New Zealand Journal of Marine and Freshwater Research, 1996: Vol 30: 455-461. Close and Rosen, 1999: National Survey of Pesticides in Groundwater – summer 1998/99. In: New Zealand Hydrological Society Conference 1999. Conference abstracts. Gregor, 2001: Arsenic removal during conventional aluminium-based drinking-water treatment. In: Water Research, Vol 35; Number 7; pp 1659-1664. Hayward S and Smith V, 1999: Groundwater contamination by hydrocarbons in Canterbury: A review of monitoring data from April 1988 to June 1999. Environment Canterbury Technical Report No R99/11. Mattingley B, 1991: New Zealand Drinking-Water Surveillance Programme. Data Review 1983 – 1989, Parts 1 and 2. DSIR Chemistry. Mattingley B, 1992: New Zealand Drinking-Water Surveillance Programme. Data Review 1983 – 1989, Parts 3 and 4. DSIR Chemistry. MoH, 1995a: Drinking-Water Standards for New Zealand 1995. Compiled by the National Drinking-Water Standards Reviewed Expert Working Group. Ministry of Health. MoH, 1995b: Guidelines for Drinking-Water Quality Management for New Zealand. Ministry of Health, Wellington. MoH, 2000a: Drinking-Water Standards for New Zealand 1995. Compiled by the National Drinking-Water Standards Review Expert Working Group. Ministry of Health. MoH, 2000b: Register of Community Drinking-Water Supplies in New Zealand:2000. Ministry of Health, Wellington. MoH, 2000c: The New Zealand Public Health Strategy. Ministry of Health, Wellington. Nokes C and Davies H, 2000: Terminal Report for Phase One of the Priority 2 Chemical Determinand Identification Programme for Assessment of Drinking-Water Standards, 1995-2000. Prepared as part of a Ministry of Health contract for scientific services. ESR, Christchurch Science Centre. Client Report No: FW0080. Nokes, 1999a: Risk factors leading to the appearance of corrosion-derived metals in drinking waters. Prepared as part of a Ministry of Health contract for scientific services. ESR, Christchurch Science Centre. Client Report No: FW9932. Nokes, 1999b: Disinfection By-products in New Zealand Drinking Waters: Occurrence; controlling factors and management. Prepared as part of a Ministry of Health contract for scientific services. ESR, Christchurch Science Centre. Client Report No: FW9978.


Rosen, 1999: The importance of long-term, seasonal monitoring of groundwater wells in the New Zealand National Groundwater Monitoring Programme (NGMP). In: New Zealand Journal of Hydrology. Volume 38, Number 1, pp 145-169. Rosen, 2001: Iron and Manganese in New Zealand groundwater: preliminary assessment of available data and directions of current research. New Zealand Hydrological Society 2001 conference abstracts, pp 94-95.


APPENDIX 1: INORGANIC DETERMINANDS OF HEALTH SIGNIFICANCE


Appendix 1.1: ANTIMONY

Table 1.1. Occurrence of antimony in community drinking-water supplies (MAV = 0.003 mg/L)

Data from Chemical Surveillance Programmes and P2

Programme Data from P2 Programme only

Total identified at > 50%

MAV Total MAV transgressions Number of zones assessed in the

P2 Programme Number of zones with determinand detected.

Limit of detection = 0.0005 mg/L (17% of MAV)

No of zones Population No of zones Population

Nationwide 23 126,278 6 2,300 859 111

Northland Health 3 1,100 1 400 94 12 Auckland Healthcare 1 150 0 0 85 5 Health Waikato 1 117,100 0 0 91 24 Pacific Health – Tauranga 0 0 0 0 24 2 Pacific Health - Rotorua 1 550 0 0 44 5 Pacific Health - Whakatane 3 3,800 0 0 21 5 Tairawhiti Healthcare 1 80 0 0 18 3 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 1 215 0 0 37 3 MidCentral Health - Wanganui 1 121 0 0 21 3 Wairarapa Health 1 120 0 0 13 3 Hutt Valley Health 0 0 0 0 36 2 Nelson Marlborough Health - Nelson 1 130 1 130 31 5 Nelson Marlborough Health - Blenheim 0 0 0 0 9 1 Crown Public Health - Christchurch 5 1,500 1 460 108 14 Crown Public Health - West Coast 1 1,107 1 1,107 26 3 Crown Public Health - Timaru 0 0 0 0 31 3 Public Health South - Dunedin 1 140 1 140 75 10 Public Health South - Invercargill 2 165 1 63 35 8

NB: Detections may outnumber the supplies assessed due to inclusion of results for the Surveillance Programmes, and because of the application of P2b, Type 1 results to zones that may not have been assessed through the P2 programme.


Table 1.2. Occurrence of antimony at greater than 50% MAV in community drinking-water zones – by source type

Source type Antimony identified at > 50% MAV

Rain water 3 Surface water 3 Ground water 16 Rain and ground water 1 Surface and ground water 0 Surface and rain water 0

Table 1.3 Occurrence of antimony at greater than 50% MAV, by zone size and type (school or community)

Zones serving a

population of greater than 500

Zones serving a population of less than 500 (excluding schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which antimony has been identified at greater than 50% MAV

5 (1.5%) 12 (3%) 6 (4.8%)


Appendix 1.2: ARSENIC

Table 2.1. Occurrence of arsenic in community drinking-water supplies (MAV = 0.01 mg/L)





P2 Programme Number of zones with determinand

detected. Limit of detection = 0.001 mg/L (10% of MAV) No of zones Population No of zones Population

Nationwide 70 284,720 28 21,284 859 152

Northland Health 1 50 0 0 94 6 Auckland Healthcare 3 7,354 0 0 85 15 Health Waikato 19 136,967 8 12,985 91 32 Pacific Health – Tauranga 1 10 1 10 24 6 Pacific Health - Rotorua 36 77,309 14 3,859 44 44 Pacific Health - Whakatane 6 12,400 4 4,400 21 14 Tairawhiti Healthcare 0 0 0 0 18 3 Taranaki Healthcare 0 0 0 0 28 3 Healthcare Hawkes Bay 2 47,900 0 0 32 7 MidCentral Health – Palmerston North 1 2,700 0 0 37 3 MidCentral Health - Wanganui 0 0 0 0 21 2 Wairarapa Health 0 0 0 0 13 1 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health - Nelson 0 0 0 0 31 1 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health - Christchurch 1 30 1 30 108 8 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health - Timaru 0 0 0 0 31 1 Public Health South - Dunedin 0 0 0 0 75 6 Public Health South - Invercargill 0 0 0 0 35 0



Table 2.2. Occurrence of arsenic at greater than 50% MAV in community drinking-water zones – by source type

Source type Arsenic identified at > 50% MAV


Table 2.3 Occurrence of arsenic at greater than 50% MAV, by zone size and type (school or community)

Zones serving a population of greater than 500

Zones serving a population of less than 500 (excluding

schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which arsenic has been identified at greater than 50% MAV

26 (7.8%) 40 (10%) 4 (3.2%)


Appendix 1.3: BARIUM

Table 3.1. Occurrence of barium in community drinking-water supplies (MAV = 0.7 mg/L)






detected. Limit of detection = 0.01 mg/L (1.4% of MAV)


Nationwide 4 287 1 30 859 592

Northland Health 0 0 0 0 94 69 Auckland Healthcare 0 0 0 0 85 63 Health Waikato 0 0 0 0 91 66 Pacific Health – Tauranga 0 0 0 0 24 25 Pacific Health – Rotorua 0 0 0 0 44 34 Pacific Health – Whakatane 0 0 0 0 21 20 Tairawhiti Healthcare 1 102 0 0 18 17 Taranaki Healthcare 0 0 0 0 28 20 Healthcare Hawkes Bay 2 160 1 30 32 27 MidCentral Health – Palmerston North 0 0 0 0 37 29 MidCentral Health – Wanganui 0 0 0 0 21 11 Wairarapa Health 0 0 0 0 13 2 Hutt Valley Health 0 0 0 0 36 19 Nelson Marlborough Health – Nelson 0 0 0 0 31 23 Nelson Marlborough Health – Blenheim 0 0 0 0 9 6 Crown Public Health – Christchurch 1 25 0 0 108 56 Crown Public Health - West Coast 0 0 0 0 26 14 Crown Public Health – Timaru 0 0 0 0 31 19 Public Health South – Dunedin 0 0 0 0 75 46 Public Health South – Invercargill 0 0 0 0 35 26



Appendix 1.4: BERYLLIUM

Table 4.1. Occurrence of beryllium in community drinking-water supplies (MAV = 0.004 mg/L)





P2 Programme Number of zones with determinand detected. Limit of detection = 0.001

mg/L (25% of MAV) No of zones Population No of zones Population

Nationwide 0 0 0 0 859 62

Northland Health 0 0 0 0 94 11 Auckland Healthcare 0 0 0 0 85 8 Health Waikato 0 0 0 0 91 4 Pacific Health – Tauranga 0 0 0 0 24 0 Pacific Health – Rotorua 0 0 0 0 44 3 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 2 Healthcare Hawkes Bay 0 0 0 0 32 2 MidCentral Health – Palmerston North 0 0 0 0 37 3 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 0 0 0 0 13 1 Hutt Valley Health 0 0 0 0 36 5 Nelson Marlborough Health - Nelson 0 0 0 0 31 2 Nelson Marlborough Health - Blenheim 0 0 0 0 9 1 Crown Public Health – Christchurch 0 0 0 0 108 8 Crown Public Health - West Coast 0 0 0 0 26 2 Crown Public Health – Timaru 0 0 0 0 31 2 Public Health South – Dunedin 0 0 0 0 75 3 Public Health South – Invercargill 0 0 0 0 35 5



Appendix 1.5: BORON

Table 5.1. Occurrence of boron in community drinking-water supplies (MAV = 1.4 mg/L)








Nationwide 8 3,372 3 1,225 859 129

Northland Health 2 230 0 0 94 22 Auckland Healthcare 3 1,532 2 1,215 85 15 Health Waikato 0 0 0 0 91 19 Pacific Health – Tauranga 1 10 1 10 24 4 Pacific Health – Rotorua 1 200 0 0 44 11 Pacific Health – Whakatane 0 0 0 0 21 9 Tairawhiti Healthcare 0 0 0 0 18 3 Taranaki Healthcare 1 1,400 0 0 28 1 Healthcare Hawkes Bay 0 0 0 0 32 10 MidCentral Health – Palmerston North 0 0 0 0 37 5 MidCentral Health – Wanganui 0 0 0 0 21 3 Wairarapa Health 0 0 0 0 13 1 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health – Nelson 0 0 0 0 31 5 Nelson Marlborough Health – Blenheim 0 0 0 0 9 1 Crown Public Health – Christchurch 0 0 0 0 108 13 Crown Public Health - West Coast 0 0 0 0 26 1 Crown Public Health – Timaru 0 0 0 0 31 2 Public Health South – Dunedin 0 0 0 0 75 3 Public Health South – Invercargill 0 0 0 0 35 1



Appendix 1.6: CADMIUM

Table 6.1. Occurrence of cadmium in community drinking-water supplies (MAV = 0.003 mg/L)








Nationwide 54 140,609 30 64,750 859 188

Northland Health 8 6,370 4 4,800 94 28 Auckland Healthcare 6 10,775 6 10,775 85 18 Health Waikato 4 1,710 2 310 91 15 Pacific Health – Tauranga 1 20,800 0 0 24 5 Pacific Health - Rotorua 6 1,733 3 943 44 12 Pacific Health - Whakatane 4 6,160 2 5,000 21 10 Tairawhiti Healthcare 1 115 1 115 18 1 Taranaki Healthcare 2 4,600 2 4,600 28 7 Healthcare Hawkes Bay 1 150 0 0 32 6 MidCentral Health – Palmerston North 1 545 1 545 37 3 MidCentral Health - Wanganui 1 1,500 0 0 21 4 Wairarapa Health 1 1,505 0 0 13 4 Hutt Valley Health 1 735 1 735 36 4 Nelson Marlborough Health - Nelson 1 130 0 0 31 4 Nelson Marlborough Health - Blenheim 1 20,502 1 20,502 9 3 Crown Public Health - Christchurch 4 2,200 3 1,900 108 23 Crown Public Health - West Coast 2 1,229 0 0 26 6 Crown Public Health - Timaru 0 0 0 0 31 4 Public Health South - Dunedin 6 44,075 3 7,800 75 15 Public Health South - Invercargill 3 15,775 1 6,725 35 16



Table 6.2. Occurrence of cadmium at greater than 50% MAV in community drinking-water zones – by source type

Source type Cadmium identified at > 50% MAV


Table 6.3 Occurrence of cadmium at greater than 50% MAV, by zone size and type (school or community)

Zones serving a population of greater

than 500


schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which cadmium has been identified at greater than 50% MAV

29 (8.7%) 18 (4.5%) 7 (5.6%)


Appendix 1.7: CHROMIUM

Table 7.1. Occurrence of chromium in community drinking-water supplies (MAV = 0.05 mg/L)






detected. Limit of detection = 0.002 mg/L (4% of MAV)


Nationwide 1 150 1 150 859 80

Northland Health 0 0 0 0 94 18 Auckland Healthcare 1 150 1 150 85 9 Health Waikato 0 0 0 0 91 3 Pacific Health – Tauranga 0 0 0 0 24 2 Pacific Health – Rotorua 0 0 0 0 44 1 Pacific Health – Whakatane 0 0 0 0 21 2 Tairawhiti Healthcare 0 0 0 0 18 5 Taranaki Healthcare 0 0 0 0 28 3 Healthcare Hawkes Bay 0 0 0 0 32 5 MidCentral Health – Palmerston North 0 0 0 0 37 3 MidCentral Health – Wanganui 0 0 0 0 21 3 Wairarapa Health 0 0 0 0 13 1 Hutt Valley Health 0 0 0 0 36 2 Nelson Marlborough Health - Nelson 0 0 0 0 31 3 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health – Christchurch 0 0 0 0 108 8 Crown Public Health – West Coast 0 0 0 0 26 2 Crown Public Health – Timaru 0 0 0 0 31 3 Public Health South – Dunedin 0 0 0 0 75 6 Public Health South – Invercargill 0 0 0 0 35 1



Appendix 1.8: COPPER

Table 8.1. Occurrence of copper in community drinking-water supplies (MAV = 2 mg/L)








Nationwide 68 55,319 24 13,405 859 832

Northland Health 10 5,860 2 370 94 98 Auckland Healthcare 6 944 2 221 85 84 Health Waikato 2 100 2 100 91 77 Pacific Health – Tauranga 3 4,620 1 120 24 24 Pacific Health - Rotorua 3 1,600 1 700 44 42 Pacific Health - Whakatane 6 6,010 3 3,610 21 23 Tairawhiti Healthcare 1 179 0 0 18 17 Taranaki Healthcare 1 200 0 0 28 29 Healthcare Hawkes Bay 3 12,771 1 65 32 30 MidCentral Health – Palmerston North 2 355 0 0 37 33 MidCentral Health - Wanganui 3 3,100 0 0 21 17 Wairarapa Health 1 350 1 350 13 12 Hutt Valley Health 1 200 0 0 36 37 Nelson Marlborough Health - Nelson 3 980 1 160 31 32 Nelson Marlborough Health - Blenheim 0 0 0 0 9 9 Crown Public Health - Christchurch 4 1,170 4 2,492 108 110 Crown Public Health - West Coast 8 11,467 4 4,098 26 26 Crown Public Health - Timaru 2 1,280 0 0 31 30 Public Health South - Dunedin 1 1,100 1 1,100 75 65 Public Health South - Invercargill 8 3,033 1 19 35 37



Table 8.2. Occurrence of copper at greater than 50% MAV in community drinking-water zones – by source type

Source type Copper identified at > 50% MAV


Table 8.3 Occurrence of copper at greater than 50% MAV, by zone size and type (school or community)


than 500


schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which copper has been identified at greater than 50% MAV

21 (6.3%) 22 (5.5%) 25 (20%)


Appendix 1.9: CYANIDE

Table 9.1. Occurrence of cyanide in community drinking-water supplies (MAV = 0.08 mg/L)









Northland Health 0 0 0 0 94 0 Auckland Healthcare 0 0 0 0 85 0 Health Waikato 0 0 0 0 91 0 Pacific Health – Tauranga 0 0 0 0 24 0 Pacific Health - Rotorua 0 0 0 0 44 0 Pacific Health - Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health - Wanganui 0 0 0 0 21 1 Wairarapa Health 0 0 0 0 13 0 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health - Nelson 0 0 0 0 31 0 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health - Christchurch 0 0 0 0 108 0 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health - Timaru 0 0 0 0 31 0 Public Health South - Dunedin 0 0 0 0 75 0 Public Health South - Invercargill 0 0 0 0 35 0



Appendix 1.10: FLUORIDE 2A

Table 10.1. Occurrence of fluoride in community drinking-water supplies (MAV = 1.5 mg/L)

Data from WINZ

Total identified at > 50% MAV

No of zones Population

Nationwide 120 1,893,344 Northland Health 1 5,000 Auckland Healthcare 33 946,474 Health Waikato 12 150,362 Pacific Health – Tauranga 0 0 Pacific Health - Rotorua 5 19,980 Pacific Health - Whakatane 2 15,000 Tairawhiti Healthcare 1 30,000 Taranaki Healthcare 9 64,057 Healthcare Hawkes Bay 6 51,672 MidCentral Health – Palmerston North 7 87,800 MidCentral Health - Wanganui 0 0 Wairarapa Health 1 19,000 Hutt Valley Health 29 346,334 Nelson Marlborough Health - Nelson 0 0 Nelson Marlborough Health - Blenheim 1 1,500 Crown Public Health - Christchurch 2 16,700 Crown Public Health - West Coast 0 0 Crown Public Health - Timaru 0 0 Public Health South - Dunedin 7 86,050 Public Health South - Invercargill 4 50,615



Appendix 1.11: FLUORIDE 2B

Table 11.1. Occurrence of fluoride in community drinking-water supplies (MAV = 1.5 mg/L)








Nationwide 3 1,465 1 63 859 44

Northland Health 0 0 0 0 94 4 Auckland Healthcare 2 1,215 1 63 85 7 Health Waikato 0 0 0 0 91 6 Pacific Health – Tauranga 0 0 0 0 24 1 Pacific Health – Rotorua 0 0 0 0 44 8 Pacific Health – Whakatane 0 0 0 0 21 1 Tairawhiti Healthcare 0 0 0 0 18 1 Taranaki Healthcare 0 0 0 0 28 2 Healthcare Hawkes Bay 0 0 0 0 32 2 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 1 250 0 0 13 1 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health – Nelson 0 0 0 0 31 0 Nelson Marlborough Health – Blenheim 0 0 0 0 9 1 Crown Public Health – Christchurch 0 0 0 0 108 8 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health – Timaru 0 0 0 0 31 0 Public Health South – Dunedin 0 0 0 0 75 1 Public Health South – Invercargill 0 0 0 0 35 1



Appendix 1.12: LEAD

Table 12.1. Occurrence of lead in community drinking-water supplies (MAV = 0.01 mg/L)








Nationwide 323 612,278 195 477,314 859 731

Northland Health 38 18,720 20 14,510 94 97 Auckland Healthcare 25 29,944 12 5,015 85 70 Health Waikato 29 152,892 18 134,590 91 60 Pacific Health – Tauranga 10 42,750 7 42,080 24 24 Pacific Health - Rotorua 28 67,566 18 60,792 44 44 Pacific Health - Whakatane 12 19,170 8 15,270 21 21 Tairawhiti Healthcare 7 437 2 201 18 13 Taranaki Healthcare 10 22,487 6 15,250 28 27 Healthcare Hawkes Bay 11 17,676 7 12,517 32 27 MidCentral Health – Palmerston North 7 2,371 6 2,071 37 31 MidCentral Health - Wanganui 3 3,100 0 0 21 13 Wairarapa Health 6 6,813 4 2,728 13 10 Hutt Valley Health 7 68,255 4 32,920 36 29 Nelson Marlborough Health - Nelson 9 6,055 5 3,005 31 23 Nelson Marlborough Health - Blenheim 8 26,902 6 26,777 9 7 Crown Public Health - Christchurch 30 19,896 19 16,450 108 78 Crown Public Health - West Coast 19 15,248 12 11,096 26 27 Crown Public Health - Timaru 15 13,550 10 11,510 31 25 Public Health South - Dunedin 23 54,600 17 52,163 75 59 Public Health South - Invercargill 26 23,846 14 18,369 35 46



Table 12.2. Occurrence of lead at greater than 50% MAV in community drinking-water zones – by source type

Source type Lead identified at > 50% MAV


Table 12.3 Occurrence of lead at greater than 50% MAV, by zone size and type (school or community)


than 500


schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which lead has been identified at greater than 50% MAV

122 (36.5%) 133 (33%) 68 (54%)


Appendix 1.13: MANGANESE

Table 13.1. Occurrence of manganese in community drinking-water supplies (MAV = 0.5 mg/L)








Nationwide 23 10,210 6 1,551 859 286

Northland Health 6 1,530 2 300 94 46 Auckland Healthcare 1 104 0 0 85 41 Health Waikato 1 360 1 360 91 28 Pacific Health – Tauranga 1 150 0 0 24 8 Pacific Health - Rotorua 1 60 0 0 44 16 Pacific Health - Whakatane 3 240 1 100 21 10 Tairawhiti Healthcare 2 791 2 791 18 8 Taranaki Healthcare 0 0 0 0 28 3 Healthcare Hawkes Bay 0 0 0 0 32 12 MidCentral Health – Palmerston North 2 600 0 0 37 11 MidCentral Health - Wanganui 3 5,900 0 0 21 10 Wairarapa Health 0 0 0 0 13 1 Hutt Valley Health 0 0 0 0 36 2 Nelson Marlborough Health - Nelson 2 375 0 0 31 8 Nelson Marlborough Health - Blenheim 0 0 0 0 9 3 Crown Public Health - Christchurch 0 0 0 0 108 32 Crown Public Health - West Coast 0 0 0 0 26 4 Crown Public Health - Timaru 0 0 0 0 31 9 Public Health South - Dunedin 0 0 0 0 75 18 Public Health South - Invercargill 1 100 0 0 35 16



Table 13.2. Occurrence of manganese at greater than 50% MAV in community drinking-water zones – by source type

Source type Manganese identified at > 50% MAV


Table 13.3 Occurrence of manganese at greater than 50% MAV, by zone size and type (school or community)


than 500

Zones serving a population of less than 500 (excluding schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which manganese has been identified at greater than 50% MAV

2 (0.6%) 16 (4%) 5 (4%)


Appendix 1.14: MERCURY

Table 14.1. Occurrence of mercury in community drinking-water supplies (MAV = 0.002 mg/L)








Nationwide 1 100 0 0 859 3




Appendix 1.15: MOLYBDENUM

Table 15.1. Occurrence of molybdenum in community drinking-water supplies (MAV = 0.07 mg/L)












Appendix 1.16: NICKEL

Table 16.1. Occurrence of nickel in community drinking-water supplies (MAV = 0.02 mg/L)








Nationwide 123 364,216 83 286,742 859 551

Northland Health 21 11,115 13 7,325 94 63 Auckland Healthcare 18 183,400 14 179,808 85 67 Health Waikato 5 1,062 4 912 91 41 Pacific Health – Tauranga 3 11,600 3 11,600 24 15 Pacific Health - Rotorua 8 56,990 3 12,550 44 26 Pacific Health - Whakatane 5 11,800 4 9,300 21 18 Tairawhiti Healthcare 0 0 0 0 18 10 Taranaki Healthcare 7 13,375 4 2,375 28 20 Healthcare Hawkes Bay 5 2,600 5 2,600 32 26 MidCentral Health – Palmerston North 5 15,675 4 15,375 37 22 MidCentral Health - Wanganui 1 1,500 1 1,500 21 13 Wairarapa Health 2 456 1 106 13 11 Hutt Valley Health 5 14,526 4 12,175 36 24 Nelson Marlborough Health - Nelson 5 2,770 2 800 31 25 Nelson Marlborough Health - Blenheim 1 600 1 600 9 4 Crown Public Health - Christchurch 8 4,280 5 1,980 108 67 Crown Public Health - West Coast 6 7,858 3 7,036 26 23 Crown Public Health - Timaru 3 8,264 2 7,784 31 13 Public Health South - Dunedin 4 1,553 3 1,453 75 35 Public Health South - Invercargill 11 14,792 7 11,463 35 28



Table 16.2. Occurrence of nickel at greater than 50% MAV in community drinking-water zones – by source type

Source type Nickel identified at > 50% MAV


Table 16.3 Occurrence of nickel at greater than 50% MAV, by zone size and type (school or community)


than 500


schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which nickel has been identified at greater than 50% MAV

55 (16.5%) 45 (11.3%) 23 (18.4%)


Appendix 1.17: NITRATE

Table 17.1. Occurrence of nitrate in community drinking-water supplies (MAV = 50 mg/L – 11.29 mg/L as nitrate N)








Nationwide 50 102,264 6 1,017 859 529

Northland Health 3 640 1 420 94 57 Auckland Healthcare 5 15,346 0 0 85 36 Health Waikato 7 779 1 191 91 58 Pacific Health – Tauranga 2 390 0 0 24 17 Pacific Health - Rotorua 1 95 0 0 44 27 Pacific Health - Whakatane 0 0 0 0 21 19 Tairawhiti Healthcare 1 102 1 102 18 6 Taranaki Healthcare 1 50 1 50 28 21 Healthcare Hawkes Bay 2 81 0 0 32 22 MidCentral Health – Palmerston North 1 70 1 70 37 19 MidCentral Health - Wanganui 1 40 0 0 21 12 Wairarapa Health 2 234 1 184 13 1 Hutt Valley Health 0 0 0 0 36 12 Nelson Marlborough Health - Nelson 4 11,090 0 0 31 24 Nelson Marlborough Health - Blenheim 1 160 0 0 9 6 Crown Public Health - Christchurch 15 72,986 0 0 108 101 Crown Public Health - West Coast 0 0 0 0 26 7 Crown Public Health - Timaru 1 130 0 0 31 24 Public Health South - Dunedin 0 0 0 0 75 30 Public Health South - Invercargill 3 71 0 0 35 30



Table 17.2. Occurrence of nitrate at greater than 50% MAV in community drinking-water zones – by source type

Source type Nitrate identified at > 50% MAV


Table 17.3 Occurrence of nitrate at greater than 50% MAV, by zone size and type (school or community)


than 500


schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which nitrate has been identified at greater than 50% MAV

6 (1.8%) 24 (6%) 20 (16%)


Appendix 1.18: NITRITE

Table 18.1. Occurrence of nitrite in community drinking-water supplies (MAV = 3 mg/L – 0.91 mg/L as nitrite N)












Appendix 1.19: SELENIUM

Table 19.1. Occurrence of selenium in community drinking-water supplies (MAV = 0.01 mg/L)








Nationwide 2 502 0 0 859 35




Appendix 1.20: SILVER

Table 20.1. Occurrence of silver in community drinking-water supplies (MAV = 0.02 mg/L)












Appendix 1.21: TIN

Table 21.1. Occurrence of tin in community drinking-water supplies (MAV = 1 mg/L)






detected, Limit of detection = 0.001 mg/L (0.1% of MAV)






APPENDIX 2: DISINFECTION BY-PRODUCTS (DBPs) OF HEALTH SIGNIFICANCE


Appendix 2.1: BROMATE

Table 2.1.1. Occurrence of bromate in community drinking-water supplies (MAV = 0.025 mg/L)





P2 Programme Number of zones with determinand detected,

Limit of detection = 0.008mg/L (32% of MAV)





Appendix 2.2: BROMODICHLOROMETHANE (THM)

Table 2.2.1. Occurrence of bromodichloromethane in community drinking-water supplies (MAV = 0.06 mg/L)






Limit of detection = 0.002mg/L (3.3% of MAV)


Nationwide 4 8,080 0 0 859 375

Northland Health 2 4,900 0 0 94 29 Auckland Healthcare 2 3,180 0 0 85 37 Health Waikato 0 0 0 0 91 58 Pacific Health – Tauranga 0 0 0 0 24 13 Pacific Health – Rotorua 0 0 0 0 44 17 Pacific Health – Whakatane 0 0 0 0 21 6 Tairawhiti Healthcare 0 0 0 0 18 5 Taranaki Healthcare 0 0 0 0 28 25 Healthcare Hawkes Bay 0 0 0 0 32 8 MidCentral Health – Palmerston North 0 0 0 0 37 22 MidCentral Health – Wanganui 0 0 0 0 21 11 Wairarapa Health 0 0 0 0 13 5 Hutt Valley Health 0 0 0 0 36 31 Nelson Marlborough Health - Nelson 0 0 0 0 31 12 Nelson Marlborough Health - Blenheim 0 0 0 0 9 3 Crown Public Health - Christchurch 0 0 0 0 108 11 Crown Public Health - West Coast 0 0 0 0 26 9 Crown Public Health - Timaru 0 0 0 0 31 12 Public Health South - Dunedin 0 0 0 0 75 49 Public Health South - Invercargill 0 0 0 0 35 12


Appendix 2.3: BROMOFORM (THM)

Table 2.3.1. Occurrence of bromoform in community drinking-water supplies (MAV = 0.1 mg/L)





P2 Programme Number of zones with determinand detected, Limit of detection = 0.001mg/L (1% of MAV)



Northland Health 0 0 0 0 94 13 Auckland Healthcare 0 0 0 0 85 27 Health Waikato 0 0 0 0 91 18 Pacific Health – Tauranga 0 0 0 0 24 1 Pacific Health – Rotorua 0 0 0 0 44 2 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 3 Healthcare Hawkes Bay 0 0 0 0 32 7 MidCentral Health – Palmerston North 0 0 0 0 37 3 MidCentral Health – Wanganui 0 0 0 0 21 4 Wairarapa Health 0 0 0 0 13 3 Hutt Valley Health 0 0 0 0 36 7 Nelson Marlborough Health - Nelson 0 0 0 0 31 0 Nelson Marlborough Health - Blenheim 0 0 0 0 9 1 Crown Public Health - Christchurch 0 0 0 0 108 0 Crown Public Health - West Coast 0 0 0 0 26 2 Crown Public Health - Timaru 0 0 0 0 31 1 Public Health South - Dunedin 0 0 0 0 75 2 Public Health South - Invercargill 0 0 0 0 35 2


Appendix 2.4: CHLORATE

Table 2.4.1. Occurrence of chlorate in community drinking-water supplies (MAV = 0.3 mg/L)






Limit of detection = 0.05mg/L (16.7% of MAV)


Nationwide 32 423,526 8 1,505 859 64

Northland Health 3 1,054 0 0 94 6 Auckland Healthcare 13 348,067 3 446 85 26 Health Waikato 7 2,020 2 460 91 10 Pacific Health – Tauranga 2 70,400 0 0 24 1 Pacific Health – Rotorua 1 151 0 0 44 1 Pacific Health – Whakatane 0 0 0 0 21 1 Tairawhiti Healthcare 1 179 1 179 18 1 Taranaki Healthcare 1 170 1 170 28 3 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 1 120 0 0 13 1 Hutt Valley Health 1 115 0 0 36 1 Nelson Marlborough Health - Nelson 0 0 0 0 31 2 Nelson Marlborough Health - Blenheim 0 0 0 0 9 2 Crown Public Health - Christchurch 1 250 1 250 108 2 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health - Timaru 0 0 0 0 31 1 Public Health South - Dunedin 1 1,000 0 0 75 6 Public Health South - Invercargill 0 0 0 0 35 0


Table 2.4.2 Occurrence of antimony at greater than 50% MAV, by zone size and type (school or community)

Zones serving a population of greater than 500


schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which chlorate has been identified at greater than 50% MAV

10 (3.0%) 17 (4.3%) 5 (4%)


Appendix 2.5: CHLOROFORM (THM)

Table 2.5.1. Occurrence of chloroform in community drinking-water supplies (MAV = 0.2 mg/L)








Nationwide 2 540 0 0 859 374



Appendix 2.6: DIBROMOACETONITRILE

Table 2.6.1. Occurrence of dibromoacetonitrile in community drinking-water supplies (MAV = 0.2 mg/L)











Appendix 2.7: DIBROMOCHLOROMETHANE (THM)

Table 2.7.1. Occurrence of dibromochloromethane in community drinking-water supplies (MAV = 0.003 mg/L)








Nationwide 0 0 0 0 859 258



Appendix 2.8: DICHLOROACETIC ACID (HAA)

Table 2.8.1. Occurrence of dichloroacetic acid in community drinking-water supplies (MAV = 0.05 mg/L)








Nationwide 38 68,123 5 3,160 859 203

Northland Health 2 750 0 0 94 20 Auckland Healthcare 0 0 0 0 85 8 Health Waikato 7 2,690 0 0 91 30 Pacific Health – Tauranga 3 13,100 0 0 24 9 Pacific Health - Rotorua 1 120 0 0 44 2 Pacific Health - Whakatane 0 0 0 0 21 1 Tairawhiti Healthcare 1 10 0 0 18 1 Taranaki Healthcare 4 5,420 1 1,500 28 20 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 4 3,275 2 775 37 13 MidCentral Health - Wanganui 2 4,100 0 0 21 8 Wairarapa Health 0 0 0 0 13 3 Hutt Valley Health 0 0 0 0 36 11 Nelson Marlborough Health - Nelson 1 20,000 0 0 31 7 Nelson Marlborough Health - Blenheim 0 0 0 0 9 3 Crown Public Health - Christchurch 1 450 0 0 108 8 Crown Public Health - West Coast 4 4,362 0 0 26 9 Crown Public Health - Timaru 0 0 0 0 31 5 Public Health South - Dunedin 8 13,846 2 885 75 34 Public Health South - Invercargill 0 0 0 0 35 11


Table 2.8.2 Occurrence of dichloroacetic acid at greater than 50% MAV, by zone size and type (school or community)

Zones serving a population

of greater than 500 Zones serving a population of

less than 500 (excluding schools)

School zones

Number of zones assessed 334 400 125 Number of zones in which dichloroacetic acid has been identified at greater than 50% MAV

18 (5.4%) 20 (5%) 0 (0%)


Appendix 2.9: DICHLOROACETONITRILE

Table 2.9.1. Occurrence of dichloroacetonitrile in community drinking-water supplies (MAV = 0.1 mg/L)











Appendix 2.10: DICHLOROMETHANE

Table 2.10.1. Occurrence of dichloromethane in community drinking-water supplies (MAV = 0.02 mg/L)











Appendix 2.11: TRICHLOROACETALDEHYDE/CHLORAL HYDRATE

Table 2.11.1. Occurrence of trichloroacetaldehyde/chloral hydrate in community drinking-water supplies (MAV = 0.01 mg/L)








Nationwide 75 233,249 17 46,975 859 195

Northland Health 9 55,350 1 300 94 18 Auckland Healthcare 1 2,190 0 0 85 12 Health Waikato 16 24,662 7 2,665 91 34 Pacific Health – Tauranga 7 21,740 0 0 24 12 Pacific Health - Rotorua 1 120 0 0 44 6 Pacific Health - Whakatane 0 0 0 0 21 1 Tairawhiti Healthcare 0 0 0 0 18 2 Taranaki Healthcare 11 55,747 2 35,940 28 17 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 6 12,675 1 230 37 13 MidCentral Health - Wanganui 5 11,540 1 2,800 21 6 Wairarapa Health 0 0 0 0 13 2 Hutt Valley Health 0 0 0 0 36 11 Nelson Marlborough Health - Nelson 3 20,600 1 150 31 5 Nelson Marlborough Health - Blenheim 0 0 0 0 9 2 Crown Public Health - Christchurch 2 700 1 450 108 5 Crown Public Health - West Coast 1 371 0 0 26 6 Crown Public Health - Timaru 1 3,500 1 3,500 31 2 Public Health South - Dunedin 8 20,072 2 940 75 31 Public Health South - Invercargill 4 3,982 0 0 35 10


Table 2.11.2 Occurrence of trichloroacetaldehyde/chloral hydrate at greater than 50% MAV, by zone size and type (school or community)




School zones

Number of zones assessed 334 400 125 Number of zones in which chloral hydrate has been identified at greater than 50% MAV

45 (13.5%) 30 (7.5%) 0 (0%)


Appendix 2.12: TRICHLOROACETIC ACID (HAA)

Table 2.12.1. Occurrence of trichloroacetic acid in community drinking-water supplies (MAV = 0.1 mg/L)








Nationwide 23 41,100 1 240 859 209

Northland Health 2 750 0 0 94 19 Auckland Healthcare 0 0 0 0 85 13 Health Waikato 3 1,920 0 0 91 31 Pacific Health – Tauranga 0 0 0 0 24 11 Pacific Health - Rotorua 0 0 0 0 44 3 Pacific Health - Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 2 Taranaki Healthcare 5 2,810 1 240 28 20 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 2 775 0 0 37 13 MidCentral Health - Wanganui 2 4,100 0 0 21 8 Wairarapa Health 0 0 0 0 13 4 Hutt Valley Health 0 0 0 0 36 7 Nelson Marlborough Health - Nelson 2 20,450 0 0 31 7 Nelson Marlborough Health - Blenheim 0 0 0 0 9 2 Crown Public Health - Christchurch 0 0 0 0 108 9 Crown Public Health - West Coast 0 0 0 0 26 8 Crown Public Health - Timaru 1 3,500 0 0 31 5 Public Health South - Dunedin 6 6,795 0 0 75 36 Public Health South - Invercargill 0 0 0 0 35 11


Table 2.12.2 Occurrence of trichloroacetic acid at greater than 50% MAV, by zone size and type (school or community)




School zones

Number of zones assessed 334 400 125 Number of zones in which trichloroacetic acid has been identified at greater than 50% MAV

12 (3.6%) 11 (2.8%) 0 (0%)


Appendix 2.13: TRICHLOROACETONITRILE

Table 2.13.1. Occurrence of trichloroacetonitrile in community drinking-water supplies (MAV = 0.001 mg/L)











Appendix 2.14: TRIHALOMETHANES (THMs)

Table 2.14.1. Occurrence of trihalomethanes in community drinking-water supplies (MAV = calc.)





P2 Programme Number of zones with determinand detected


Nationwide 34 76,123 2 4,900 859

Northland Health 9 51,030 2 4,900 94 Auckland Healthcare 8 10,920 0 0 85 Health Waikato 5 2,183 0 0 91 Pacific Health – Tauranga 0 0 0 0 24 Pacific Health - Rotorua 0 0 0 0 44 Pacific Health - Whakatane 0 0 0 0 21 Tairawhiti Healthcare 0 0 0 0 18 Taranaki Healthcare 2 360 0 0 28 Healthcare Hawkes Bay 0 0 0 0 32 MidCentral Health – Palmerston North 4 5,075 0 0 37 MidCentral Health - Wanganui 2 5,150 0 0 21 Wairarapa Health 0 0 0 0 13 Hutt Valley Health 0 0 0 0 36 Nelson Marlborough Health - Nelson 1 150 0 0 31 Nelson Marlborough Health - Blenheim 0 0 0 0 9 Crown Public Health - Christchurch 2 700 0 0 108 Crown Public Health - West Coast 0 0 0 0 26 Crown Public Health - Timaru 0 0 0 0 31 Public Health South - Dunedin 1 555 0 0 75 Public Health South - Invercargill 0 0 0 0 35


Table 2.14.2 Occurrence of THMs at greater than 50% MAV, by zone size and type (school or community)




School zones

Number of zones assessed 334 400 125 Number of zones in which THMs have been identified at greater than 50% MAV

17 (5.1%) 17 (4.3%) 0 (0%)


Appendix 2.15: HALOACETIC ACIDS (HAAs)

Table 2.15.1. Occurrence of HAAs in community drinking-water supplies (MAV = calc.)







Nationwide 71 16,1980 28 55,814 859

Northland Health 4 5,850 2 750 94 Auckland Healthcare 1 270 0 0 85 Health Waikato 13 6,645 4 2,220 91 Pacific Health – Tauranga 5 17,160 1 6,000 24 Pacific Health - Rotorua 1 120 0 0 44 Pacific Health - Whakatane 0 0 0 0 21 Tairawhiti Healthcare 1 10 0 0 18 Taranaki Healthcare 11 57,447 5 5,660 28 Healthcare Hawkes Bay 0 0 0 0 32 MidCentral Health – Palmerston North 8 9,175 3 2,375 37 MidCentral Health - Wanganui 3 6,300 2 4,100 21 Wairarapa Health 1 2,580 0 0 13 Hutt Valley Health 0 0 0 0 36 Nelson Marlborough Health - Nelson 3 20,600 1 20,000 31 Nelson Marlborough Health - Blenheim 2 4,000 0 0 9 Crown Public Health - Christchurch 2 700 1 450 108 Crown Public Health - West Coast 4 4,362 2 3,964 26 Crown Public Health - Timaru 1 3,500 1 3,500 31 Public Health South - Dunedin 11 23,261 6 6,795 75 Public Health South - Invercargill 0 0 0 0 35


Table 2.15.2 Occurrence of HAAs at greater than 50% MAV, by zone size and type (school or community)




School zones

Number of zones assessed 334 400 125 Number of zones in which THAAs has been identified at greater than 50% MAV

37 (11.1%) 33 (8.3%) 1 (0.8%)


Appendix 2.16: BROMOCHLOROACETIC ACID

Table 2.16.1. Occurrence of bromochloroacetic acid in community drinking-water supplies (No MAV)






Limit of detection = 0.005 mg/L.





Appendix 2.17: DIBROMOACETIC ACID

Table 2.17.1. Occurrence of dibromoacetic acid in community drinking-water supplies (No MAV)











Appendix 2.18: MONOCHLOROACETIC ACID

Table 2.18.1. Occurrence of monochloroacetic acid in community drinking-water supplies (No MAV)











Appendix 2.19: BROMOCHLOROACETONITRILE

Table 2.19.1. Occurrence of bromochloroacetonitrile in community drinking-water supplies (No MAV)











Appendix 2.20: BROMOCHLOROMETHANE

Table 2.20.1. Occurrence of bromochloromethane in community drinking-water supplies (No MAV)











Appendix 2.21: DIBROMOMETHANE

Table 2.21.1. Occurrence of dibromomethane in community drinking-water supplies (No MAV)











Appendix 2.22: 1,1-DICHLOROPROPAN-2-ONE

Table 2.22.1. Occurrence of 1,1-dichloropropan-2-one in community drinking-water supplies (No MAV)











Appendix 2.23: 1,1,1-TRICHLOROPROPAN-2-ONE

Table 2.23.1. Occurrence of 1,1,1-trichloropropan-2-one in community drinking-water supplies (No MAV)











APPENDIX 3: PESTICIDES OF HEALTH SIGNIFICANCE


Appendix 3.1: ALDRIN & DIELDRIN

Table 3.1.1. Occurrence of aldrin & dieldrin in community drinking-water supplies (MAV = 0.00003 mg/L)






detected. Limit of detection = 0.00001 mg/L (33% of MAV). No of zones Population No of zones Population

Nationwide 2 360 0 0 859 3

Northland Health 1 150 0 0 94 1 Auckland Healthcare 0 0 0 0 85 0 Health Waikato 0 0 0 0 91 0 Pacific Health – Tauranga 0 0 0 0 24 0 Pacific Health – Rotorua 0 0 0 0 44 0 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 0 0 0 0 13 0 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health - Nelson 0 0 0 0 31 0 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health - Christchurch 0 0 0 0 108 1 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health - Timaru 0 0 0 0 31 0 Public Health South - Dunedin 0 0 0 0 75 0 Public Health South – Invercargill 1 210 0 0 35 1


Appendix 3.2: SIMAZINE

Table 3.2.1. Occurrence of simazine in community drinking-water supplies (MAV = 0.002 mg/L)










Appendix 3.3: 2,4,5-T

Table 3.3.1. Occurrence of 2,4,5-T in community drinking-water supplies (MAV = 0.01 mg/L)










Appendix 3.4: TERBUTHYLAZINE

Table 3.4.1. Occurrence of terbuthylazine in community drinking-water supplies (MAV = 0.008 mg/L)






detected. Limit of detection = 0.0002 mg/L (2.5% of MAV). No of zones Population No of zones Population




Appendix 3.5: TRICLOPYR

Table 3.5.1. Occurrence of triclopyr in community drinking-water supplies (MAV = 0.1 mg/L)








Northland Health 0 0 0 0 94 0 Auckland Healthcare 0 0 0 0 85 0 Health Waikato 0 0 0 0 91 1 Pacific Health – Tauranga 0 0 0 0 24 0 Pacific Health – Rotorua 0 0 0 0 44 0 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 0 0 0 0 13 0 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health – Nelson 0 0 0 0 31 0 Nelson Marlborough Health – Blenheim 0 0 0 0 9 0 Crown Public Health – Christchurch 0 0 0 0 108 0 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health – Timaru 0 0 0 0 31 0 Public Health South – Dunedin 0 0 0 0 75 1 Public Health South – Invercargill 0 0 0 0 35 0


APPENDIX 4: OTHER ORGANICS OF HEALTH SIGNIFICANCE


Appendix 4.1: ACRYLAMIDE

Table 4.1.1. Occurrence of acrylamide in community drinking-water supplies (MAV = 0.0005 mg/L)










Appendix 4.2: BENZENE

Table 4.2.1. Occurrence of benzene in community drinking-water supplies (MAV = 0.01 mg/L)








Northland Health 0 0 0 0 94 0 Auckland Healthcare 0 0 0 0 85 0 Health Waikato 0 0 0 0 91 0 Pacific Health – Tauranga 0 0 0 0 24 0 Pacific Health – Rotorua 0 0 0 0 44 1 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 0 0 0 0 37 1 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 0 0 0 0 13 0 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health - Nelson 0 0 0 0 31 0 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health – Christchurch 0 0 0 0 108 1 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health – Timaru 0 0 0 0 31 0 Public Health South – Dunedin 0 0 0 0 75 1 Public Health South – Invercargill 0 0 0 0 35 0


Appendix 4.3: DI(2-ETHYLHEXYL)PHTHALATE

Table 4.3.1. Occurrence of Di(2-ethylhexyl)phthalate in community drinking-water supplies (MAV = 0.009 mg/L)

Data from Chemical Surveillance Programmes and P2 Programme

Data from P2 Programme only





Nationwide 1 121 0 0 859 5

Northland Health 0 0 0 0 94 1 Auckland Healthcare 0 0 0 0 85 0 Health Waikato 0 0 0 0 91 1 Pacific Health – Tauranga 1 121 0 0 24 1 Pacific Health – Rotorua 0 0 0 0 44 1 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 1 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health - Wanganui 0 0 0 0 21 0 Wairarapa Health 0 0 0 0 13 0 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health - Nelson 0 0 0 0 31 0 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health - Christchurch 0 0 0 0 108 0 Crown Public Health - West Coast 0 0 0 0 26 0 Crown Public Health - Timaru 0 0 0 0 31 0 Public Health South - Dunedin 0 0 0 0 75 0 Public Health South - Invercargill 0 0 0 0 35 0


Appendix 4.4: 1,4-DICHLOROBENZENE

Table 4.4.1. Occurrence of 1,4-Dichlorobenzene in community drinking-water supplies (MAV = 0.4 mg/L)






detected. Limit of detection = 0.0005 mg/L (0.1 % of MAV). No of zones Population No of zones Population


Northland Health 0 0 0 0 94 0 Auckland Healthcare 0 0 0 0 85 0 Health Waikato 0 0 0 0 91 0 Pacific Health – Tauranga 0 0 0 0 24 0 Pacific Health – Rotorua 0 0 0 0 44 0 Pacific Health – Whakatane 0 0 0 0 21 0 Tairawhiti Healthcare 0 0 0 0 18 0 Taranaki Healthcare 0 0 0 0 28 0 Healthcare Hawkes Bay 0 0 0 0 32 0 MidCentral Health – Palmerston North 0 0 0 0 37 0 MidCentral Health – Wanganui 0 0 0 0 21 0 Wairarapa Health 0 0 0 0 13 0 Hutt Valley Health 0 0 0 0 36 0 Nelson Marlborough Health - Nelson 0 0 0 0 31 0 Nelson Marlborough Health - Blenheim 0 0 0 0 9 0 Crown Public Health – Christchurch 0 0 0 0 108 0 Crown Public Health – West Coast 0 0 0 0 26 0 Crown Public Health – Timaru 0 0 0 0 31 0 Public Health South – Dunedin 0 0 0 0 75 0 Public Health South – Invercargill 0 0 0 0 35 1


Appendix 4.5: ETHYLBENZENE

Table 4.5.1. Occurrence of ethylbenzene in community drinking-water supplies (MAV = 0.3 mg/L)










Appendix 4.6: FLUORANTHENE

Table 4.6.1. Occurrence of Fluoranthene in community drinking-water supplies (MAV = 0.004 mg/L)










Appendix 4.7: TETRACHLOROETHENE

Table 4.7.1. Occurrence of tetrachloroethene in community drinking-water supplies (MAV = 0.05 mg/L)










Appendix 4.8: TOLUENE

Table 4.8.1. Occurrence of toluene in community drinking-water supplies (MAV = 0.8 mg/L)










Appendix 4.9: 1,1,1-TRICHLOROETHANE

Table 4.9.1. Occurrence of 1,1,1-trichloroethane in community drinking-water supplies (MAV = 2 mg/L)










Appendix 4.10: TRICHLOROETHENE

Table 4.10.1. Occurrence of Trichloroethene in community drinking-water supplies (MAV = 0.08 mg/L)










Appendix 4.11: o-XYLENE

Table 4.11.1. Occurrence of o-Xylene in community drinking-water supplies (MAV = 0.6 mg/L)










Appendix 4.12: m+p-XYLENE

Table 4.12.1. Occurrence of m+p-Xylene in community drinking-water supplies (MAV = 0.6 mg/L)









Documents

A REPORT ON THE CHEMICAL QUALITY OF NEW ZEALAND’S ... · A Report on the Chemical Quality of New Zealand’s June 2001 Community Drinking Water Supplies 3.7.3 Conclusions, implications