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Drinking water 2005 Part 3 Thames region A report by the Chief Inspector Drinking Water Inspectorate

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Drinking water 2005Part 3 Thames region

A report by the Chief InspectorDrinking Water Inspectorate

Drinking Water Inspectorate | 55, Whitehall | London | SW1A 2EY | Tel: 0207 082 8024

http://www.dwi.gov.uk

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Drinking water 2005

Part 3

Thames region

A report by the Chief Inspector Drinking Water Inspectorate

June 2006

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Published by Drinking Water Inspectorate 55 Whitehall London SW1A 2EY Tel: 020 7082 8024 Website: http://www.dwi.gov.uk

© Crown Copyright 2006

ISBN: 1-905852-06-1

ISBN: 978-1-905852-06-2

PB11881f

Copyright in the typographical arrangement and design rests with the Crown.

This publication (excluding the logo) may be reproduced free of charge in any format or medium provided that it is reproduced accurately and not used in a misleading context. The material must be acknowledged as Crown copyright with the title and source of the publication specified.

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Thames region Contents

Letter from the Chief Inspector of Drinking Water to the Secretary of State for the Environment, Food and Rural Affairs and the Minister of State (Climate change and the environment) 1

Introduction 9

Thames region 11

Water sources 12

Drinking water quality testing 12

Drinking water quality results 13

Water quality in distribution 29

Consumer perceptions of drinking water quality 32

Issues of local interest 34

Incidents in 2005 35

Technical audit activity in the region 36

Local authority consultation 38

Consultation with health professionals 39

Annex 1: Other sources of information 41

Annex 2: Glossary and description of standards 43

Annex 3: Incidents in the Thames region in 2005 57

Annex 4: Water regulation and management MSc 65

This report is Part 3 of three parts published annually by the Drinking Water Inspectorate. Part 3 consists of regional reports for Eastern, Midlands, Northern, Southern, Thames, Western and Wales regions.

Part 1 – Drinking water standards and science outlines how water is regulated, how to find more information about drinking water and presents a review of research.

Part 2 – Drinking water safety reviews the performance of the water industry in 2005.

All reports are available on the Inspectorate’s website at http://www.dwi.gov.uk and on CD.

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DRINKING WATER INSPECTORATE 55, Whitehall, London. SW1A 2EY

Direct Line: 020 7082 8048 Enquiries: 020 7082 8024 Facsimile: 020 7082 8028

28th June 2006

To

The Rt Hon David Miliband MP Secretary of State for the Environment, Food and Rural Affairs and Ian Pearson MP Minister of State (Climate Change and the Environment)

I am pleased to present the 16th report about drinking water quality in England and Wales covering the year ending 31 December 2005. Building on the success of the new approach to reporting introduced last year, this year my report is in portfolio format using a range of technologies thereby enabling broad community access to drinking water quality information. I have made public access to information a priority for the Inspectorate because I believe this is vital to consumer confidence. Below I summarise the purpose and content of each part of my report.

Part 1 Drinking water standards and science is a booklet which explains straightforwardly how drinking water quality in England and Wales is measured and regulated. Also included is advice on how someone can access the science which underpins the standards and a summary of Defra’s Drinking Water Quality & Health Research Programme managed by the Inspectorate. The booklet, which explains what someone should do if they have a concern about drinking water quality, will be distributed widely to public libraries, the Consumer Council for Water and local authorities.

Part 2 Drinking water safety I expect this part of my report to be of direct interest to water companies, policy makers, other regulators and opinion formers. In it, I outline safe drinking water management practice and report on the performance of the water industry in England and Wales in terms of this framework using a basket of measures derived from data currently available to the Inspectorate. This information reflects the differing challenges faced by each of the water companies in terms of the nature of their water resources and their water treatment and distribution infrastructure, as well as the influence on drinking water quality of domestic (building) water systems maintained by their customers. It also contains a summary of the AMP4 drinking water quality improvement programme.

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Part 3 Regional drinking water quality reports. This is a series of booklets, one for each of the six regions in England describing the drinking water quality results in 2005. The audiences for these reports are local community stakeholders, particularly local authorities and health professionals, but also importantly members of the regional Consumer Council for Water committee. Each of these booklets includes a commentary by the Inspectorate on test results and water company actions in response to any adverse findings, together with details of learning from water quality incidents and technical audits carried out by Inspectors. Details are also given of progress in the year with drinking water improvement programmes, consumer perceptions and outcomes of consultations with local authorities and with health professionals.

Electronic Information A CD comes with the folder that contains the above mentioned booklets. On the CD are Look Up Tables of the results of drinking water tests by water company. The CD also provides Parts 1, 2 and 3 of the Report in electronic format.

Website publication The booklets and Look Up tables are available on the Inspectorate’s website in downloadable format. The website is also where people can find the entirety of the Inspectorate’s guidance, research reports and other facts and figures of public interest such as our prosecution and enforcement record.

Drinking water quality in 2005 As explained in some detail in my report last year, drinking water quality is measured in zones containing no more than 100,000 consumers. By calculating the mean zonal compliance % for forty parameters, we have a broad measure of overall compliance by water companies with European and national drinking water standards. For the whole of England in 2005 this compliance figure was 99.96% compared to 99.94% in 2004. As a whole therefore the picture for 2005 is one of improvement from the baseline set in 2004 (the first year of reporting against the new standards). In 2005, for 17 parameters compliance was 99.99% or above. For a further 15 parameters it was between 99.95% and 99.99%. The three parameters with the lowest figures were the same as for 2004 – lead (99.77%), iron (99.66%), nickel (99.64%). The problems reflected by these parameters do not apply everywhere. Details of their occurrence are described in my relevant regional reports. Discoloured water due to iron is most severe in the north and the south west of the country whereas nickel arising from the nature of groundwater is confined to the east. Lead is a more complex subject which I review more fully below.

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Meeting the current and future lead standards

The pipe connecting a property to the water company main, together with internal plumbing, is the main source of lead in drinking water. The extent of lead pick up depends on various factors; temperature, acidity (pH), water hardness, the length of pipe and the time that water is left to stand in the pipe (stagnation) before it is drawn off. Properties built or renovated since 1970 are unlikely to have lead pipes and since 1990 water companies have opportunistically replaced many of their service connections as part of their water distribution maintenance programmes.

In 1996 the World Health Organisation (WHO) tightened its guideline of 50 µg/l for lead in drinking water because lead can accumulate in the body and this can give rise to adverse neurological health effects in young children. When setting the new guideline of 10 µg/l, WHO recognised that the permanent solution, removal of lead pipes, would take time and money to achieve. The view of WHO was that other practical measures (water treatment) should be introduced in the interim. This WHO advice was adopted formally in Europe through the 1998 Drinking Water Directive, which set an interim standard of 25 µg/l (December 2003) and a final standard of 10 µg/l (to become effective in 2013). The extent of lead in drinking water in England was described by the Department of the Environment in the mid 70’s as ‘two thirds of households with virtually no lead but 10% of homes exceeding 50 µg/l.’

In England and Wales phosphate dosing was adopted as the most cost effective way of treating the water to make it less likely to dissolve lead from pipes and solder. The companies have now installed phosphate dosing in most places where the need has been identified and during 2005 dosing levels have been optimized. The extent of supplies now being treated is illustrated by a map in each of my regional reports this year. It is important to realize that the risk of consumer exposure to lead is limited to only those properties with lead pipes. The companies collect samples for lead testing from properties selected at random at a rate of about 24,000 per year but consumers can also ask their water company to take a sample from their home if they suspect lead may be present. Companies have reported carrying out more than 4,000 additional tests on behalf of consumers in 2005.

All the work done on lead to date has resulted in an overall improving trend for England and Wales shown in the figure below. Looking towards the future and based on monitoring during 2005 only a very small fraction (0.26%) of tests now give results above the tightened interim standard of 25 µg/l and the number of tests failing the future standard of 10 µg/l is in decline.

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England and Wales: Percentage of tests meeting the current and future standard for lead 2001 to 2005

Meeting the lead standard everywhere by 2013 will be a complex matter because not all owners of buildings will choose to invest in replacing lead pipes, even when notified of an adverse test result by their water company. However because by law water companies notify local authorities of the location of every sample containing lead above 25 µg/l the Inspectorate is recommending that the way forward is for local authorities to begin actively reviewing this information. To assist this process a map of the location of samples exceeding the standards has been included in each regional report. Local health professionals are best placed to determine if any additional action is justified to reduce exposure to lead in a particular community. Locations of particular interest might be social housing and public buildings such as schools.

Public buildings

For several years there has been debate in the industry about where responsibility should lie for testing drinking water quality in public buildings. This controversy has its roots in the fact that some drinking water quality experts in water companies have the firm view that sampling public buildings would increase the investigative work they have to carry out in response to the results of coliform indicator tests in particular. Another factor behind this concern is the fact that the European Drinking Water Directive at the moment only recognises the responsibility of owners for building water system maintenance in domestic properties, not in public buildings.

In 2005, the Inspectorate asked companies to identify the samples in their programmes collected from public buildings. All but five companies reported they had collected samples from public buildings. Overall about 3% of nearly 142,000 samples were from public buildings although some companies sampled at a higher rate (maximum 10%).

94

95

96

97

98

99

100

2001 2002 2003 2004 2005

Year

% M

eetin

g S

tand

ard

25 µg/l10 µg/l

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From analysis of this information I can report that only 1 in 218 public building samples required investigative work compared to 1 in 221 samples from domestic properties. There is therefore no evidence to support the undue burden argument of water companies and my Inspectors will be checking to ensure that all companies sample a similar and reasonable proportion of public buildings in future.

Events affecting drinking water quality in 2005

In my regional reports I give details of events and incidents notified in 2005. In England and Wales as a whole a total of 92 incidents were notified in 2005 as compared to 89 incidents in 2004. The details of each of these incidents are of particular interest to local authorities and health professionals therefore I have again this year published such information (in my regional reports) together with the findings of the investigating Inspector. Even in the most well run of companies incidents will happen. What matters is how well a company minimises both the risk of occurrence and the consequences of incidents, acting to protect public health at all times. Information about incidents is, I believe, of particular benefit to the work of the Consumer Council for Water. It also serves as a basis for dialogue and learning in local drinking water quality and health professional forums.

In 2005, in both England and Wales, health authorities reported a higher than usual number of cases of cryptosporidiosis in the autumn. A number of outbreaks were recognised, one in the north of Wales and two in the south of England and outbreak control teams were established promptly. Longer term surveillance by the Health Protection Agency has shown that cases of cryptosporidiosis due to the human strain Cryptosporidium hominis are more frequent in autumn than at other times of the year whereas the well recorded spring time peak of cases due to Cryptosporidium parvum (animal origin) has virtually disappeared. On the basis of available information I wrote to water companies in December 2005 (Information Letter 17/2005) on the subject of their Cryptosporidium risk assessments (a regulatory requirement). I asked companies to provide the Inspectorate with updated risk assessments for surface water sources by the end of April 2006. Additionally and in the same time frame, the Inspectorate commissioned a report from the Health Protection Agency to formally update health surveillance information and knowledge of the organism since the publication in 1998 of the Third Report of the Expert Group on Cryptosporidium in Water Supplies. These actions will contribute to the evidence I require to give my advice later this year about the adequacy of the arrangements in place to safeguard consumers from waterborne outbreaks of cryptosporidiosis.

I felt it was in the public interest for the Inspectorate to carry out very extensive and thorough investigations of the two cryptosporidiosis incidents potentially linked by early descriptive epidemiology to a source of water for public water supplies. Amongst their many tasks my Inspectors took statements from consumers in North Wales diagnosed as suffering from cryptosporidiosis and these accounts are a testament to the severity and consequences of the illness suffered.

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In my regional reports for Wales and the Southern region in England I describe the outbreaks in more detail. I am pleased to record that the water companies concerned have co-operated fully with the Inspectorate’s investigations, more importantly they worked closely with local health officials to help bring both outbreaks under control as quickly as practicable. The Inspectorate’s findings and conclusions regarding these incidents are not included in this report because at the time of its preparation the offence of supplying water unfit for human consumption was under consideration.

Water safety plan approach In Part 2 of this report I outline best practice regarding drinking water safety and present a view of the performance of each water company, and the industry as a whole, using a basket of measures set within the World Health Organisation’s water safety framework. I hope this picture will result in a more informed dialogue between all who have a part to play in the safe management of our drinking water supplies. I have also published details of the data used and the method of calculation of each of the measures.

During the year I observed that it is not uncommon for media reporting of comments made by opinion formers, academics and advocates for the environment to give the false impression that a contaminant in a natural water body equals poison pouring out of consumers’ taps everywhere. Similarly discussions about the importance of protecting water sources and the undesirability, as a matter of principle, of end of pipe solutions (water treatment) often revealed misunderstandings about how the safety of drinking water quality is assured, particularly regarding the extent and scope of treatment applied to drinking water for particular substances. Noting this gap in knowledge I have this year published, in Part 2 of this report, details of the water treatment in place at the end of 2005, and that planned for the future. What is most evident from this information is the very different challenge faced by each of the companies. This demonstrates one of the important principles of the WHO water safety plan approach, namely that each individual water supply chain requires a comprehensive risk assessment and a well communicated risk management strategy.

Training drinking water professionals for the future Changes in the industry over the past 15 years have led to discussions and a growing concern about the best means of developing drinking water professionals to equip them with the full range of skills and knowledge required to ensure water supplies are managed to protect public health. I am pleased therefore to announce that the Inspectorate has taken steps to address this concern by working in partnership with the University of Surrey to develop and deliver a flexible programme of either full time or part time study leading to an internationally accredited postgraduate qualification for engineers and scientists. Full details are published as an annex in this report, the course is available for the first time in 2006 and I commend it to the industry.

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The duty of everyone to safeguard drinking water I am very pleased that the new Consumer Council for Water has announced in its forward programme of work that it will be working closely with the Inspectorate to ensure that consumers are adequately informed about drinking water quality matters including their own responsibilities. If something goes wrong with drinking water it can be something of an automatic reaction of consumers to point the finger of blame at the water company. However, sometimes the remedy lies rather closer to home. In 2005, companies informed the Inspectorate of various situations which had come to their attention where the owner had failed to maintain the domestic water systems inside their buildings.

The degree of neglect illustrated in the photographs below is regrettably neither atypical nor uncommon. It is in everyone’s interest that consumers are supported by appropriate information and advice about how to look after their domestic water supply. The Inspectorate has been working with WHO and others to develop simple risk assessment protocols for use by those responsible for domestic water systems in public and commercial buildings and for private water supplies.

Consequences of uncovered tanks Consequences of inappropriate tank location

Professor Jeni Colbourne MBE Chief Inspector of Drinking Water

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Introduction The Chief Inspector’s report ‘Drinking Water 2005’ on the quality of drinking water in England and Wales is presented in a series of publications.

Part 1 – Drinking water standards and science provides information on how drinking water quality is measured and regulated. It sets out the responsibilities of the Drinking Water Inspectorate and various other organisations in the protection of water and public health. It also explains how to resolve issues with drinking water quality and gives details of the latest drinking water science and research programme.

Part 2 – Drinking water safety describes best practice on drinking water safety and sets out the performance of the industry and individual companies in these terms.

This document is one of a series of regional reports on drinking water quality comprising Part 3 – Regional reports.

In total there are seven regional reports designed to meet the needs of local authorities and consumers through their Consumer Council for Water (CCWater). The Consumer Council for Water is made up of regional Committees, the boundaries of which determine the scope of each report as shown on the map below.

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The regional reports follow the above boundaries and are designed to provide information on drinking water quality which is focussed on local issues and written in a way to make the science and regulations easily accessible.

The report provides an insight into a number of aspects of drinking water quality. Not only does it inform on the outcome of tests taken for microbiological, physical and chemical parameters in the region and the reasons for any failures to meet standards, but it also uses maps to show variations in drinking water quality for iron, manganese, lead and fluoride across the region. Additionally an overview of incidents occurring in the region, their cause and outcome, is given with a view to sharing learning. We include topics of local interest, chosen because they illustrate an interesting event or development or that they explain the background to a local issue related to water quality. We report on the technical audit work of our inspectors by describing the audits carried out in the region and their main findings. The contact that consumers have with their water companies on the subject of drinking water quality is also presented. Finally, the regional reports serve as a means for us share the feedback received from local authorities and health professionals.

This year, for the first time, the Inspectorate will distribute the reports more widely by providing libraries in England and Wales with copies as well as ensuring that they can be accessed from the Inspectorate’s website at http://www.dwi.gov.uk

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Thames region

Key facts

Population supplied Amount of water supplied l/day Number of local authorities

11,838,000 3,862 million65

Treatment works Service reservoirs Water supply zones

201 551 331

(with a further 17 partially covering the region) Length of mains pipe (km) 48,927

Area of supply Bedfordshire (part), Berkshire (part), Buckinghamshire (part), Essex (part), Gloucestershire (part), Hampshire (part), Hertfordshire, Kent (part), Inner London, Outer London (part), Oxfordshire, Surrey (part), West Sussex (part), Warwickshire (part), Wiltshire (part).

Water composition Surface sources Ground water sources Mixed sources

62% 35% 3%

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Water sources Three water companies supply drinking water in the Thames region: Sutton and East Surrey Water (SES), Thames Water (TMS) and Three Valleys Water (TVW).

Much of the water supplied in the region is surface water (62%) abstracted from lowland rivers such as the Thames, Lee, Colne, Kennet, Eden, Cherwell, New and Tillingbourne. Most of this river water is held in large raw water storage reservoirs before being drawn off for treatment. Reservoirs, such as Farmoor (Oxford), Bough Beech (Edenbridge) and those such as Wraysbury, near Heathrow airport, provide strategic water storage for times when demand for water exceeds the volume that can be taken from rivers.

Groundwater provides a valuable resource across the region (35%). Most of the boreholes draw groundwater from the chalk, oolytic limestone and greensand aquifers. Across the region a small proportion (3%) of water supplies are mixtures of surface and groundwater sources.

Thames water has a licence to supply drinking water to Tidworth in Wiltshire. Information on water quality in the Thames Tidworth zone is reported separately in the Western region report.

In the Thames region there are some rural areas where there are no public water supplies. A small number of local authorities are aware of a significant number of private supplies. For example, Cherwell District Council (165), South Oxfordshire (225) and West Oxfordshire District Council (150). Mole Valley District Council reported 10 supplies, which is more typical for the region. Responsibility for checking the safety and sufficiency of private water supplies in the region rests with the local authorities. The role of the Drinking Water Inspectorate in respect of private supplies is to provide expert technical advice to the Secretary of State, local authorities and owners of private water supplies. A consultation will be taking place during the summer of 2006 on the future form of private water supply regulation. Further information can be found at www.defra.gov.uk

Drinking water quality testing Throughout 2005, water companies sampled drinking water across the region to test for compliance with the standards in the Water Supply (Water Quality) Regulations 2000. More than one half of the tests were carried out on drinking water drawn from consumers’ taps selected at random. For monitoring purposes, company water supply areas are divided into zones based on population (maximum 100,000). Generally zones are sampled at consumer taps with the number of required tests being greatest in zones with larger populations. Other sample locations are water treatment works and treated water (service) reservoirs. Collectively the three water companies carried out a total of 678,221 tests during 2005. Only 430 of these tests failed to meet the standards set down in the regulations.

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Table 3.5.1 Number of tests carried out by companies in the region

Sutton and East

Surrey Water Thames Water Three Valleys

Water Total

Water treatment works

16,096 (9)

103,958 (103)

76,348 (81)

196,402 (193)

Service reservoirs 8305 (32)

94,287 (365)

34,586 (135)

137,178 (532)

Consumers’ taps (zones)

19,890 (19)

241,524 (242)

83,227 (70)

344,641 (331)

Number of tests per company

44,291 439,769 194,161 678,221

Estimate of population

641,000 8,231,000 2,966,000 11,838,000

Note 1: Numbers in brackets reflect the number of works, reservoirs or zones operated by that company in 2005 in the region. Some companies are permitted to carry out some tests on samples taken from supply points rather than from consumers’ taps. Note 2: Tests in the Thames Water Tidworth zone in the Western region have been omitted from the totals.

The regulations require companies to test for specified parameters at prescribed frequencies. Most of the testing is for parameters with European or National standards (mandatory quality standards), and these results are discussed here. Water companies are also required by the regulations to test for other indicator parameters such as ammonium, sulphate and colony counts. A summary of the results of testing by each company, including the indicator parameters can be found on the DWI website and on the CD accompanying this report.

Drinking water quality results The key water quality results for the Thames region are presented in two tables, one showing results for microbiological parameters (Table 3.5.2), the other dealing with chemical and physical parameters (Table 3.5.4). The microbiological quality of water is discussed first. Companies report all results of tests on a monthly basis to the Inspectorate.

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Microbiological quality

Table 3.5.2: Microbiological parameters

Parameter Current

Standard Total number

of tests

No. of tests not meeting

the standard

Additional Information

Water leaving water treatment works

E.coli 0/100ml 28,019 1 TMS (1)

Coliform bacteria 0/100ml 28,020 10 SES (3), TMS (6), TVW (1)

Cryptosporidium

<1 oocyst per 10 litres

Treatment Standard

5,571 0

Monitored at 16 works in the region determined to be at risk, out of a total of 193.

Water leaving service reservoirs

E.coli 0/100ml 27,436 2 TMS (1), TVW (1)

Coliform bacteria

0/100ml in 95% of tests

at each reservoir

27,436 39

Two reservoirs in the Thames region out of 532 did not meet the annual 95% compliance rule: Westerham Hill (TMS) and Knockholt Old (TMS). SES (2), TMS (34), TVW (3)

Water sampled at consumers’ taps

E.coli 0/100ml 30,622 12 TMS (11), TVW (1).

Enterococci 0/100ml 2,651 1 TMS (1)

Notes: Summary details of all microbiological tests undertaken by each water company can be found on the DWI website and on the CD accompanying this report.

To protect public health, microbiological standards have to be met at each individual treatment works and service reservoir. The results confirm the overall microbiological safety of drinking water supplies in the region. The significance of the individual test results for each microbiological parameter at each location varies and a single positive result cannot be interpreted without other information. All companies are expected to follow best practice as set out in The Microbiology of Drinking Water (2002) published by the Standing Committee of Analysts (SCA). Information about the SCA can be found in Part 1 of the report, available on the DWI website and on the CD accompanying this report.

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E.coli at works

In 2005, a total of 28,019 tests at works were carried out by all the companies across the region. E.coli was detected in only one sample. On detecting E.coli, companies are required to act promptly to protect public health. Their immediate response when finding E.coli at a works is to sample again and more widely to confirm that water being received by consumers is safe. In 2005 these additional tests gave satisfactory results in all cases and there were no subsequent E.coli failures in 2005.

Thames Water reported that a treated water sample taken in November from Speen works (Newbury) contained E.coli. In response to the Inspectorate initiating enforcement action, the company has provided information suggestive of an error in the sampling/testing process. There was no evidence of a contamination of water supplied to consumers. The Inspectorate is continuing to closely monitor the situation.

Table 3.5.3 Detection of E.coli and Enterococci at treatment works, service reservoirs and consumers’ taps

E.coli in water leaving

treatment works

E.coli in water leaving service

reservoirs

E.coli at consumers’

taps

Enterococci at consumers’

taps

Sutton and East Surrey Water

0/2,312 0/1,661 0/1,665 0/152

Thames Water 1/13,334 1/18,858 11/21,348 1/1,970

Three Valleys Water 0/12,373 1/6,917 1/7,609 0/529

Region overall 1/28,019 2/27,436 12/30,622 1/2,651

Note: Results are shown as the number of positive tests/the total number of tests.

Coliform bacteria at works

Testing for coliform bacteria gives reassurance that water is being treated adequately to remove bacterial and viral pathogens. Repeated occurrences of coliform bacteria in samples at the same works in one year are thus of concern and require action to be taken. In 2005, this situation occurred at one of the 193 works in the region. Two samples (May and June) from Walton works, near Hampton Court, contained coliform bacteria. Thames Water’s investigations found a problem with the sampling facilities. The company now collects samples from a different location and subsequent results have been satisfactory during 2005. The Thames Water investigation of a single coliform failure at the Datchet/Eton works resulted in repairs to cracks in the contact tank and replacement of the sampling facilities. Improvements to sampling facilities were also made following a positive coliform detection at the Streatham works.

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There was one occasion where Three Valleys Water reported results on samples taken at a time when the water treatment works was out of service. The company have been required to provide an explanation for this discrepancy.

Cryptosporidium at works

The regulations require companies to monitor for this parasite at those works assessed to be at significant risk. In 2005 monitoring was required to be undertaken at 16 works (1 SES, 12 TMS, 3 TVW). All results met the regulatory treatment standard of <1 oocyst per 10 litres and there were no reports of mains water supply related outbreaks of cryptosporidiosis in the region.

Improvement works to enhance treatment to reduce Cryptosporidium risk were completed at three works in the region during 2005; Swinford works (TMS), Elmer and Dorking works (SES).

E.coli at service reservoirs

In 2005, across the region, a total of 27,436 tests were carried out at service reservoirs by all the companies. E.coli was detected on one occasion at two locations in a sample at the following service reservoirs: Knockholt Old reservoir operated by Thames Water, and Rye Hill reservoir owned by Three Valleys Water.

On detecting E.coli, companies are required to act promptly to protect public health. The immediate response when finding E.coli at a service reservoir is to sample again and more widely to confirm that water being received by consumers is safe. In 2005 these additional tests all gave satisfactory results and there were no subsequent E.coli failures.

In August, Thames water detected E.coli at Knockholt Old reservoir (near Sevenoaks). They removed a section of old timber from inside a hatch cover that was thought to be the source of the contamination. Following the third detection of coliforms in November 2005 Thames Water removed the reservoir from service and performed an internal inspection. The company carried out work to improve the integrity of the reservoir structure. There have been no further failures at this site since it was returned to service in January 2006.

At Rye Hill reservoir (near Harlow) in August, after an E.coli failure, Three Valleys Water sampled more widely to confirm that water being received by consumers was safe. The company had carried out an internal reservoir inspection in December 2004. After a further external inspection in December 2005 the company decided to implement some improvements to reservoir integrity in 2006.

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Coliform bacteria at service reservoirs

Testing for coliform bacteria gives reassurance that the quality of water held at these strategic points in the distribution system is adequately maintained. The national standard requires that at least 95% of samples collected weekly from each service reservoir throughout one year are free from all coliform bacteria. In 2005 all but two service reservoirs (including water towers) in the region met the standard. The action taken by Thames Water in relation to the Knockholt Old service reservoir site is described above.

At Westerham Hill reservoir (Westerham), four samples in 2005 contained coliform bacteria. Investigations by Thames Water concluded that these were linked to a defect with the sampling pump and sample line. As a consequence of the Inspectorate initiating enforcement action the company has implemented an enhanced monitoring programme and replaced the sampling pipework along with the associated valve. The company plan to drain down and inspect the reservoir in 2006 when operational conditions permit.

Thames Water will be undertaking an inspection of Bishops Wood B reservoir (near Highgate), where coliforms have been detected, as soon as facilitating valve works have been completed at Ashford Works, meanwhile the Inspectorate is closely monitoring the situation.

After detecting a coliform failure in September at the Highgate service reservoir, Thames Water carried out an internal inspection which identified points of rainwater ingress which were rectified. The reservoir was returned to service on 12 October. The following day there was a second coliform failure. The company then took the reservoir out of supply, drained and refilled it before returning the reservoir to service. The company is to install a new roof at the reservoir in 2006. Potential ingress points were identified and repaired by the company at two other sites following single coliform failures in 2005 (Kiddepore and Stow Hill reservoirs).

Following a single positive coliform sample at Kew Bridge North reservoir (Brentford), Thames Water removed the reservoir from service for an internal inspection. The reservoir was disinfected, sample lines replaced and the sample sink relocated. A further failure occurred during the time that the new sampling lines were being installed. Following completion of these works no further failures occurred in 2005. Thames Water also carried out improvements to the sampling facilities at two other service reservoirs with coliform failures (Winchester Wood 1 North and Blacklains B). Sutton & East Surrey Water upgraded the sample facilities at the Langley Park reservoir following a single failure in October (see Annex 3 for details).

Single failures were identified within a period of two days at Sibford and Shennington reservoirs and Bretch water tower. Thames Water attributed these failures to a problem with the booster chlorination system at the pumping station supplying these sites. At Bretch tower (near Banbury) a redundant length of sampling line was removed.

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It is not possible to assess compliance for the Stow Hill B reservoir (TMS) because fewer than 50 samples were taken in 2005.

There were a number of occasions when Three Valleys reported results for samples taken on dates when the service reservoir was out of service. The company have been required to provide an explanation for this discrepancy.

The Inspectorate has noted that coliform bacteria were found in 39 samples from service reservoirs in the Thames region during the year and this information will inform the Inspectorate’s risk based programme of technical audit.

E. coli and Enterococci at consumers’ taps

A total of 30,622 consumer taps were tested in 2005 for E.coli and 12 were positive (11 TMS, 1 TVW). There was no indication, from information gathered by the two water companies, of a faecal contamination event affecting other properties in these zones.

In four out of 12 cases Thames Water found evidence of a hygiene problem at the consumer’s tap. Through a sampling survey Three Valleys Water was able to reassure the Inspectorate that the single consumer tap failure was not indicative of a wider problem.

For the remaining seven samples reported by Thames Water the Inspectorate initiated enforcement action. In response the company has made improvements to its protocol for investigating detections of faecal indicator organisms at consumers’ taps. The Inspectorate is closely monitoring the situation to ensure that any future positive samples receive a prompt and thorough investigation and appropriate evidence is generated to reassure the Inspectorate and local authorities regarding the absence of a wider contamination event.

Like E.coli the presence of Enterococci is indicative of faecal contamination and neither bacterium should be found in any sample. In 2005, the companies carried out 2,651 tests for Enterococci at consumers’ taps. Only one sample (1 TMS) was positive. There was no indication, from information gathered by the water company, of a faecal contamination event affecting other properties in this zones.

Chemical quality

The Water Quality (Water Supply) Regulations 2000 set out the minimum testing requirements for all chemical and physical parameters. A summary of the results of testing by each company, including the results for indicator parameters is provided on the DWI website and on the CD accompanying this report.

The table and text below set out the results for those parameters where there has been a failure to meet a European or National standard (mandatory quality standards). In addition, due to local authority interest, the results of testing for fluoride, iron, lead, manganese, nitrate, nitrite and pesticides are given.

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Table 3.5.4 Chemical and physical parameters

Parameter Current standard

Total number of tests

Number of tests not

meeting the standard

Additional Information

Aesthetic parameters – colour – odour – taste

20 mg/l pt/Co

3 at 25˚C 3 at 25˚C

6,670 6,641 6,599

1 1 4

TMS (1) TMS (1) TMS (4)

Aluminium 200 µg/l 6,298 1 TVW (1)

Antimony 5 µg/l 2,547 4 TMS (4)

Bromate 10 µg/l 1,616 2 TVW (2)

Fluoride 1.5 mg/l 2,452 0

Iron 200 µg/l 8,308 22 SES (1), TMS (16), TVW (5)

Lead (current standard) Lead (future standard)

25 µg/l

10 µg/l

11,819

11,819

44

300

TMS (44) Further information including a map and graph can be found with the text below

Manganese 50 µg/l 5,877 4 TMS (3), TVW (1)

Nickel 20 µg/l 2,554 9 TMS (8), TVW (1)

Nitrate 50 mg/l 7,890 3 TMS (3)

Nitrite 0.5 mg/l 7,895 0

Pesticides – Total 0.5 µg/l 1,533 1 TMS (1)

Pesticide – Individual (see note 3)

0.1 µg/l 41,975 2 Diuron – TMS (1) Simazine – TVW (1)

Sodium 200 mg/l 2,542 1 TMS (1)

Turbidity 4 NTU 7,987 4 SES (1), TMS (1), TVW (2)

Notes: 1. For summary details of all tests undertaken by each water company refer to the DWI website or the CD accompanying this report. 2. For comparison, 1 mg/l is one part in a million, 1 µg/l is one part in a thousand million. 3. A further 2,400 tests were done for aldrin, dieldrin,heptachlor, heptachlor epoxide, all of which met the relevant standard.

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Aluminium

Aluminium can occur naturally in some drinking water sources. Also, aluminium based water treatment chemicals may be used at surface water works to aid the process of filtration.

In 2005, a total of 6,298 samples were tested for aluminium in the Thames region. Sutton and East Surrey Water and Thames Water achieved 100% compliance with the aluminium standard. Just one test exceeded the standard (TVW) and this was not related to process control at the works. Three Valleys Water’s investigation found that the exceedance in the Wembley zone in September was caused by the localised disturbance of deposits accumulated in the distribution network following a burst main. Tests for other standards (iron and turbidity) on the sample also gave unsatisfactory results. The company flushed the main to remove deposits.

Antimony

Antimony is not normally found in water sources. Trace concentrations in drinking water can be derived from brass tap fittings and from solders. In 2005 a total of 2,547 tests were carried out for antimony and all but four met the standard (5 µg/l).

The four exceedances were all reported by Thames Water, one each in four different zones. The results ranged from 5.5 to 17.8 µg/l. Three of the failures occurred over a two day period in January (Charlton, North Downs, and Thamesmead zones) and one in April (Crouch End zone). Further samples from the properties and nearby hydrants on mains were satisfactory. As a result of the Inspectorate’s consideration of these results, the company’s laboratory has decided to change the type of bottle used for collecting samples for analysis for antimony. The Inspectorate is closely monitoring the situation.

Bromate

Normally bromate is only formed in drinking water when bromide is present in surface water treated with ozone. The process of chlorination may also produce bromate, for example, through the use of sodium hypochlorite solution containing bromide or when chlorine is generated on site by electrolysis. In the past three years, companies have put in place control measures aimed at meeting the standard of 10 µg/l, which was new in 2004.

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In the Thames region, out of a total of 1,616 tests, the standard was exceeded on two occasions in 2005. Both failures were reported by Three Valleys Water, with one in July relating to an existing ground water contamination which is discussed below. The company linked the failure in December to the use of a batch of a salt with a high bromide concentration at the Runley Wood Greensand works (near Luton). Operating procedures were revised to ensure only low bromide salt is used in the future for on site generation of chlorine.

Three Valleys Water first discovered bromate contamination of raw water at their Hatfield source in May 2000. As reported in Drinking Water 2004, extensive investigations confirmed pollution of the chalk aquifer from the site of a former chemical works in Sandridge. Following the designation of the site as contaminated land in 2002, four potentially appropriate persons (under the Environmental Protection Act, 1990, Part IIA) were identified in 2003. In November 2005, the Environment Agency served a legal notice under section 78E of the Environmental Protection Act 1990 on two companies who had previously occupied the site (Redland Minerals Limited and Crest Nicholson Residential plc). This notice required these companies to investigate and monitor the extent of the plume of pollution.

There has been no remediation to date and it is the water companies who are managing the consequences and protecting consumers through blending and monitoring. During 2005, Three Valleys Water and Thames Water entered into legally binding agreements for longer term measures to prevent bromate in the groundwater affecting drinking water supplies. These measures include: a replacement for the Hatfield source at Nomansland (TVW) and treatment at Sherrardswood works; abandonment of the Essendon works and drilling of two new boreholes to provide a replacement supply to be treated at Bulls Green and Essendon via North Mymms works; additional treatment at Bulls Green works (TVW) and enhanced treatment at Hornsey works (TMS).

Despite the arrangements in place in July 2005 Three Valleys Water detected 10.4 µg/l of bromate in a sample from the Hatfield/Potters Bar zone. The company’s investigation found that heavy rainfall had caused a sudden increase in raw water bromate levels at its Essendon works. The short term treatment (GAC) and blending arrangements were insufficient to deal with the changed conditions, however, samples showed that conditions had returned to normal within two days. The Inspectorate initiated enforcement action to enable the company to revise the programme of work to take the situation into account.

Progress with the work at Hornsey (TMS) has been delayed by issues relating to planning permission however, the company is striving to complete the work within the agreed timescale. The Inspectorate will continue to monitor progress with all these schemes which are due to be operational by December 2008.

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Fluoride

Traces of fluoride occur naturally in many water sources, particularly in groundwaters. For example fluoride is found in water abstracted by Three Valleys Water from the Reading Beds in West Essex, and in an area south of Reading (around Burghfield and Tadley) supplied by Thames Water. Figure 3.5.5 provides information on the average fluoride level recorded in each zone (2004/05 data combined) in the region. Consumers should obtain specific information on the level of fluoride in the drinking water supply to their home or workplace from their water company.

Figure 3.5.5 Average fluoride levels in zones for 2004/05

Fluoride is not removed by conventional water treatment. Some companies fluoridate water supplies at the request of the local health authority as a protection against tooth decay. The Inspectorate is not aware of any fluoridation schemes currently operating in the Thames region. In 2005, all 2,452 tests for fluoride taken across the region met the regulatory standard (1.5 mg/l). For more information on fluoridation please refer to the DWI website (http://www.dwi.gov.uk).

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Lead

The pipe connecting a property to the water company main, together with internal plumbing, is the most common source of lead in drinking water. The extent of lead pick up depends on various factors; temperature, acidity (pH), water hardness, the length of pipe and the time that water is left to stand in the pipe (stagnation) before it is drawn off. Properties built or renovated since 1970 are unlikely to have lead pipes and since 1990 water companies have opportunistically replaced many service connections as part of their water distribution maintenance programmes. For example, at least 445,000 service pipes were replaced between 1991 and 1994.

In 1996 the World Health Organisation (WHO) tightened its guideline for lead in drinking water because lead can accumulate in the body and this can give rise to adverse neurological health effects in young children. When setting the new guideline of 10 µg/l, WHO recognised that the permanent solution, removal of lead pipes, would take time and money to achieve. The extent of the challenge in the UK is illustrated by a government report for 1975 – 76 (DoE) which showed that whilst two thirds of households had virtually no lead, 10% of homes in England and 33% of homes in Scotland had levels in drinking water above the original guideline of 50 µg/l at that time. The view of WHO was that other practical measures (water treatment) should be introduced in the interim. This WHO advice was adopted formally in Europe through the 1998 Drinking Water Directive, which set an interim standard of 25 µg/l (December 2003) and a final standard of 10 µg/l (to become effective in 2013). In the UK it was determined that phosphate dosing was the most cost effective way of treating the water and making it less likely to dissolve lead from pipes and solder.

Table 3.5.6 Percentage of lead tests meeting the 25 µg/l standard from 2001 to 2005

2001 2002 2003 2004 2005

Sutton and East Surrey Water

99.83% 99.59% 99.82% 98.68% 100%

Thames Water* 97.94% 97.73% 99.75% 99.43% 99.60%

Three Valleys Water 98.95% 99.79% 98.90% 99.43% 100%

Note: The 25 µg/l standard was not a regulatory requirement until 25 December 2003 *Excluding the Tidworth water supply zone which is in the Western region.

In the Thames region, steady progress has been made by each company towards meeting the new standards. The improving trend for the region can be seen in figure 3.5.7. Looking towards the future and based on monitoring during 2005 it appears that less than three percent (2.5%) of drinking water taps in properties in the region are likely to exhibit lead at levels greater than the standard of 10 µg/l. Although small this is the highest frequency of all the regions in England due to a combination of factors such as density and age of housing stock in the cities of Oxford and London.

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Figure 3.5.7 Percentage of tests meeting the current and future standard for lead between 2001 and 2005 in the region

95

96

97

98

99

100

2001 2002 2003 2004 2005

Year

% M

eetin

g S

tand

ard

25 µg/l 10 µg/l

The companies have completed their initial programmes of water treatment measures and during 2005 all companies have been optimising phosphate dosing levels. The area now covered by schemes in the region is illustrated in figure 3.5.8. The extent and location of failures reported by companies as part of their regulatory sampling programme in both 2004 and 2005 is also shown on the map. It is important to realise that the risk of consumer exposure to lead is limited to only those properties with lead pipes. Although many properties will not yet have been sampled as part of the companies’ regulatory monitoring programmes, consumers can request that their water company take a sample from their home if they suspect lead may be present. In 2005, companies in the Thames region reported 985 consumer requests of this nature.

Meeting the lead standard is a complex matter because not all owners of buildings will choose to replace lead pipes, even when notified of an adverse test result by their water company. Also some lead in drinking water is due to the use of lead solder on copper pipes and fittings (despite the fact that the use of lead solder for drinking water installations was banned in the early 1970’s). Brass fittings provide a further source of lead in some buildings.

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Figure 3.5.8 Maps showing the distribution of lead results above the existing and future standard, along with the extent of zones covered by an improvement programme

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As part of the regulatory programme of tap sampling, water companies notify local authorities of the location of every sample containing lead above 25 µg/l. The Inspectorate recommends that local authorities actively review this information to identify ‘hot spots’ in their area where additional measures may be required to reduce exposure to lead. For example, in the Thames region there are clusters of lead failures in parts of Oxfordshire (Abingdon and the city of Oxford) and North and Central London (Bush Hill Park, Chelsea, Cheshunt, Enfield, Goff’s Oak and Wanstead). Locations of particular interest to local authorities might be schools and other similar public buildings or social housing. Most water companies will replace their part of a service pipe when the building owner indicates they wish to remove the domestic lead plumbing. This good practice is something that local authorities may wish to promote and the Inspectorate encourages companies, local and health authorities to develop joint communication programmes in ‘hot spot’ areas.

Nickel

Nickel may be present in coatings on modern tap fittings. In 2005 a total of 2,554 tests were carried out for nickel and all but nine met the standard (20 µg/l). The maximum value detected was 77 µg/l. In five cases (4 TMS, 1 TVW) the company’s investigation was able to link the findings to the consumers tap fittings. In the remaining cases (TMS) there was no evidence of a wider problem with samples taken from neighbouring properties or nearby hydrants having nickel levels well below the standard.

Two of the related failures occurred in one Thames Water zone (Thatcham South) and these probably typify the role of consumers plumbing. In one case the sampler noted that a water filter and softener had been fitted and in the other case nickel plated taps had recently been installed in the kitchen. On both occasions the company wrote to the consumer with advice.

Nitrate and nitrite

Nitrate occurs naturally in all source waters due to the natural decay of vegetable material in soil. Nitrogenous fertilisers used on arable farmland are a significant source of nitrate in groundwater. Rainfall washes nitrate from the soil in to lakes, rivers and streams. Nitrate levels can be reduced by water treatment or by blending with another, low nitrate, water source.

In 2005, a total of 7,890 tests were carried out and all but three (TMS) met the standard (50 mg/l). A level of 77.0 mg/l was recorded in the North Kensington zone in May. This sample also failed to meet the nitrate/nitrite formula standard. All investigational samples from the area were well below the standard and typical of nitrate levels in the zone (maximum 32.2 mg/l). Thames Water also reported levels of 83.6 mg/l and 85.0 mg/l in samples taken from consumers’ taps in the Osterley Park and Mile End zones over a three day period in December 2005. A fault with laboratory equipment used for nitrate testing was identified. Subsequent investigation samples were satisfactory.

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An improvement programme to treat for nitrate reduction (ion exchange) was completed early at Ashdown Park (TMS) by 31 December 2005. This allows water from Fognam Down boreholes to be transferred to the new plant at Ashdown Park and for the subsequent closure of the treatment works at Fognam Down. The treatment works at Green Street Green was also closed down by 31 December 2005, as required by an agreed programme of work, with the raw water from the boreholes being transferred to a new treatment works at Land End.

During 2005, legally binding agreements were put in place to enhance the treatment to remove nitrate at two Thames Water works (Sheafhouse and Wilmington works) and two works owned by Three Valleys Water (Chipping and Offley Bottom). A further legally binding agreement was put in place for Thames Water to abandon its Blewbury works and increase abstraction from another source to compensate. The schemes at Sheafhouse and Blewbury were completed on schedule by 31 December 2005. The remaining schemes are due for completion between September 2006 and March 2010.

Nitrite may be formed when chloramine is used as the residual disinfectant to maintain the microbiological quality in the distribution network. The formation of nitrite is controlled by careful optimisation of the disinfection process. Chloramine is widely used for water supplies in London, in addition chloraminated water from Anglian Water’s Grafham works is imported to supply customers of Three Valleys Water in the Luton area. Nitrite can also form in samples of water, after collection and before analysis, especially if the sample is not kept cool. In 2005, all 7,895 tests carried out across the region for nitrite met the standard.

Pesticides and related products

This group of substances generically called pesticides, includes many organic chemicals with a wide range of uses such as weed killers, insecticides and fungicides. Water sources may contain traces of pesticide residues as a result of agricultural use (pest control on crops) and non-agricultural use (herbicide for weed control on highways etc.). Water companies are required to assess the risk to drinking water from pesticide use in their catchments and then test for those individual pesticides that might be present. There are standards for individual pesticides as well as a standard for the sum of all the pesticides. The standards are set with a wide safety margin. Many works in the region now have treatment capable of removing most pesticides in general use. Companies are expected to keep up to date their list of pesticides used in the catchment for each source.

In 2005, one of the tests in the region exceeded the standard for total pesticides (TMS). There was 100% compliance (2,400 tests) for the four pesticides with a standard of 0.03 µg/l. Out of a total of 41,975 tests for individual pesticides (with a standard of 0.1 µg/l) just two exceeded the standard for Diuron (1 TMS) and Simazine (1 TVW). When herbicides are first detected, water companies take action to protect consumers, enhance their monitoring programme and where appropriate pass details to the Environment Agency.

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Diuron

Diuron is a non-selective herbicide mainly used to control weeds on hard surfaces. In 2005, Thames Water detected the substance at levels above the standard in a single sample taken from Addington works (New addington). This result (0.69 µg/l) also exceeded the standard for total pesticides. The site was taken out of service until levels of the herbicide in the raw water had reduced to well below the drinking water standard. The company suspects that a single point-source contamination event occurred within the source protection zone. Additional monitoring of the raw water is being undertaken and the company are liaising with local landowners about herbicide usage in the catchment area. All subsequent samples taken from this site during 2005 met the standard.

Simazine

Simazine is a herbicide used to control the growth of grasses and broad-leaved weeds. In 2005, Three Valleys Water detected the substance at levels above the standard in a single sample taken from Southall in the Southall/Feltham zone (0.11 µg/l). Simazine levels in the River Thames (which supplies the area) are usually below 0.1 µg/l. All subsequent samples taken from this site during 2005 met the standard.

During 2005, Thames Water entered into a legally binding agreement to install granular activated carbon (GAC) treatment at its Netley Mill works (near Guildford) to remove the herbicide atrazine. The work is due to be completed by December 2006. Three Valleys Water entered into a legally binding agreement to install enhanced treatment at its Kensworth Lynch works (near Luton) to remove chlorotoluron. This work is due to be completed by March 2008. In addition, the company completed a short term programme of improvements in 2005 at Mymms works to reduce mecoprop concentrations. Monitoring in the zones supplied by each of these works during 2005 has confirmed that all samples complied with the pesticide standard.

Sodium

Elevated levels of sodium in drinking water are most likely to occur as a result of a water softener being installed by the owner of the property. Good practice for a householder seeking to reduce scaling of appliances is to arrange for installation of the softening equipment in such a way that water drawn for human consumption continues to come direct from the mains.

In 2005, a total of 2,542 tests were carried out for sodium across the region and all but one met the standard (200 mg/l). A level of 260.4 mg/l sodium was detected by Thames Water in a sample from a consumers’ tap in the Twyford Wargrave & Sonning zone where a water softener was installed.

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Water quality in distribution Iron and manganese may be present naturally in raw water, iron compounds may be added as part of water treatment or it can be released as a consequence of the corrosion of iron mains. The most severe problems tend to be where the distribution network contains a large proportion of old cast iron mains. Effective water treatment reduces iron and manganese at source, but if treatment is not effective, iron and manganese may collect in distribution pipes. When these deposits are disturbed, they may cause orange-brown or black discolouration of the water. Elevated levels of iron and manganese can also result in breaches of the turbidity standard.

Table 3.5.9 Compliance by company with the standards for iron, manganese and turbidity

% Compliance Iron Manganese Turbidity

Sutton and East Surrey Water

99.78% 100% 99.78%

Thames Water 99.74% 99.89% 99.99%

Three Valleys Water 99.84% 99.96% 99.95%

Region overall 99.76% 99.91% 99.97%

Note: For more information on % parameter compliance please refer to the DWI website or the CD accompanying this report.

Figure 3.5.10 shows the distribution of iron and manganese failures in zones across the region. The map highlights one zone where the standard for iron (200 µg/l) was exceeded on more than one occasion in 2005.

Two failures of the iron standard occurred in the Luton North zone. Three Valleys Water carried out a sampling survey and devised a flushing exercise to clean deposits from the mains in this area. Following this work no further exceedances were found during 2005.

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Figure 3.5.10 Map showing the distribution of failures, along with the extent of zones covered by an improvement programme

The map also shows the areas where the water companies carried out a legally binding programme of improvement work under Section 19 of the Water Industry Act 1991. Table 3.5.11 below confirms that all three companies in the region have now completed there long term programmes of work to replace or refurbish cast iron mains.

Figure 3.5.11 Progress with Section 19 distribution system improvement programmes

Length of main replaced or refurbished

in 2005

Length of main still to

be replaced or refurbished

Renovation completed

Completion due

Sutton and East Surrey Water

2.1 km None Nov 2005 N/A

Thames Water None None Dec 2002 N/A

Three Valleys Water 12.0 km None Mar 2005 N/A

Region overall 14.1 km 0.0

Note: The dates are updated from those published in Drinking Water 2004

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Even though the three companies in the region have completed their section 19 programmes of work, the Inspectorate will continue to closely monitor that the companies’ maintenance programmes are sufficient to ensure compliance in the future. The trend between 1997 to 2005 is illustrated in the graph (Figure 3.5.12).

Figure 3.5.12 Trends in operational performance

99.0

99.5

100.0

1997 1998 1999 2000 2001 2002 2003 2004 2005

Inde

x (%

)

Sutton and East Surrey Water Thames Water Three Valleys Water

Note: Trends relate to results for three parameters – iron, manganese and turbidity

As can be seen from figure 3.5.10, some of the failures that occurred in 2005 were in areas where the company was carrying out a programme of work. Most failures were isolated occurrences not indicative of a wider problem of compliance with the iron, manganese or turbidity standards.

Sutton and East Surrey Water reported a turbidity and iron failure in the Bough Beech zone in November which was linked to an incident (see Annex 3).

Thames Water reported a turbidity result of 6.6 NTU in a sample taken from a school kitchen in the Lewisham zone during the school holiday. Samples from local hydrants were satisfactory and low water use in the building was the likely cause of the failure.

Three Valleys Water reported two samples with results above the turbidity standard. The first taken from a consumers’ property in the Pirbright/Send zone also failed the iron standard. Repairs to a nearby fire hydrant were being undertaken at the time of sampling and this probably disturbed deposits in the local pipework. The second in the company’s Wembley zone also failed the aluminium and iron standard. A burst main in the locality was the likely reason for these results.

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Aesthetic parameters

Consumers expect their drinking water to be not only safe to drink, but also clear with no discernible taste or odour. In recognition of this the regulations stipulate national standards for colour, odour and taste. In 2005, all tests in the region met the standard with the following exceptions:

• Thames Water reported one sample that exceeded the standard for colour for which no explanation was found. Further samples were satisfactory

• Thames Water reported one sample that exceeded the odour standard. The sample taken from a consumer’s property in the Kilburn zone was described as having a ‘chemical/paint’ type odour. The sampler had noticed that the kitchen was being decorated at the time. Samples of the local supply were satisfactory

• Thames Water reported four samples that exceeded the taste standard, each from separate premises in four different zones. Investigations showed that in two of these premises there was a domestic water softener fitted and in a third there was a plumbed in water filter. On each occasion the consumer was provided with advice about how to reduce the adverse affects of such devices. Samples from the local water supply were satisfactory in all these cases.

Consumer perceptions of drinking water quality When consumers have a question or a concern about drinking water quality their first point of contact is the water company. The Inspectorate held a workshop with companies in the autumn of 2005 to develop definitions for drinking water quality consumer contacts. These definitions and guidance on recording and reporting consumer contacts are contained in Information Letter 1/2006 ((website reference). Two companies (THM, SES) in the Thames region were able to provide the Inspectorate with the full range of consumer contact data for 2005 and this is summarised in table 3.5.13. The data provided by Three Valleys Water was incomplete therefore figures in table 3.5.13 are estimates made by the Inspectorate drawing on overall industry figures.

Table 3.5.13 Summary of consumer contacts about drinking water quality in 2005

App

eara

nce

Tast

e an

d

odo

ur

Repo

rt o

f

illne

ss

Wat

er

qual

ity

conc

ern

Info

rmat

ion

re

que

st

Tota

l nu

mbe

r

of c

ont

acts

Con

tact

rat

e

per

1,0

00

pop

ula

tio

n

Sutton and East Surrey Water

70% 18% 3% 6% 4% 686 1.07

Thames Water 32% 10% 3% 7% 48% 12,795 1.55

Three Valleys Water 58% 26% (1%) (2%) (12%) (7,109) (2.40)

Region overall 8,642 3,261 (503) (1,155) (7,033) (20,590) (1.74)

Note: figures in brackets are estimates based wholly or partly on industry average

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In line with published evidence, consumer perceptions in the region are strongly influenced by the appearance of their drinking water with 42% of all contacts being about the appearance of drinking water. Although many of these contacts from consumers in the Thames region were about discoloured water due to the accumulation and suspension of deposits in water mains close to half (3,991) were reports of white water which happens when air becomes entrained in water. This confirms the importance of continued work by companies on the causes and remedies of discoloured water (see section on Water quality in distribution). However, white water events have received much less attention from water companies, even though their impact on consumer perceptions can be very pronounced. For example, out of the 79 appearance contacts received by Sutton and East Surrey during the whole of 2005 from a single zone, 51 (65%) were reports of white water. Thames Water recorded at least eight zones where white water reports were more than three quarters of the total appearance contacts, the most severe case being a zone where white water reports were responsible for 96% (83 out of 86) of appearance contacts. The Inspectorate believes companies can and should do more to identify the root cause of white water events and take steps to prevent them.

There were 1,751 contacts about chlorine (54% of all taste contacts) in 2005 from consumers in the Thames region. A recent cross national study of drinking water quality perceptions by the University of East Anglia found a greater tendency towards chemo phobic attitudes in the UK than on the continent. The Inspectorate considers that water companies need to take greater account of these societal attitudes recognising, for example, that consumers do not perceive chlorine in drinking water as beneficial and fluctuating or higher than necessary levels of chlorine in drinking water will cause consumers to react adversely.

Access to information is important to consumer confidence and in 2005 Thames Water and Sutton and East Surrey Water together provided drinking water quality reports to 930 consumers on request. From their detailed record keeping Thames Water has demonstrated a significant consumer demand in the region for information about water hardness (82% of all information requests). The Inspectorate believes that companies in hard water areas might usefully collaborate with their local Consumer Council for Water to proactively communicate the facts of hard water.

When the response of a company to a consumer contact about drinking water quality fails to provide the necessary reassurance or remedy then the consumer may complain directly to the Inspectorate. In 2005, there were 28 consumers in the region who were sufficiently dissatisfied with the water company to complain to the Inspectorate. The majority (26) were customers of Thames Water, 12 of these related to the appearance of water and 7 were about an objectionable taste. As a general rule, when a consumer comes to the Inspectorate it is because the company has not provided the consumer with appropriate, sufficient or timely information.

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Consumers who turn to the Inspectorate often display a lack of trust in their water company and, excluding the very occasional vexatious caller, a complaint to the Inspectorate should be regarded as a significant opportunity for learning and improvement by the company’s senior management.

Issues of local interest Buncefield oil depot fire

In the early hours of Sunday 11th December 2005, a number of explosions occurred at Buncefield Oil Storage Depot, Hemel Hempstead, Hertfordshire. Significant damage occurred to both commercial and residential properties in the vicinity and the fire burned for several days. Three Valleys Water responded to the incident and assisted the emergency services making water available for fire fighting and providing local knowledge to the multi agency team led by the Environment Agency set up to manage the environmental impact of the incident.

Drinking water supplies to consumers in the area were not directly affected by the incident, however, Three Valleys Water took the precautionary step of fitting of non-return valves close to the site (preventing the risk of contamination by backflow of water from the site). The local supply arrangements were also reconfigured with some assets remaining out of supply.

Water used to fight the fire (so called firewater) was collected in bunds on site, and later removed to secure off-site storage. However some firewater did escape from the site. This water is likely to have contained hydrocarbons and polycyclic aromatic compounds (a group of chemicals commonly found in residues from burning coal, fuel and oil) and residues of fire-fighting foam (which contains zinc and a chemical called perfluorooctane sulphonate or PFOS).

The Environment Agency is the lead agency in the team as regards the delivery of the environmental monitoring arrangements (see http://www.environment-agency.gov.uk/)

Three Valleys and the Drinking Water Inspectorate agreed that the situation would be managed using normal operational procedures i.e. the company would notify the Inspectorate of results obtained by it, or notified to it by the Environment Agency.

For further information on the Buncefield investigation see http://www.buncefieldinvestigation.gov.uk/index.htm.

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Use of herbicides on railway land

The water industry has an agreement with Network Rail to protect water resources from herbicides used to control weeds along railway lines. This is a national agreement, coordinated by the Environment Agency, but it is of particular relevance to the Thames region where the scheme originated primarily due to the large number of suburban and mainline railways throughout the region, particularly around London. Many of these railway lines necessarily run close to surface and groundwater sources and many of these had been affected by the herbicide (atrazine) historically used on the railways.

As a result of the protection measures of Network Rail and its predecessors, atrazine levels in some water sources have fallen noticeably and there has not been any corresponding increase in diuron, the pesticide normally used as an alternative. This agreement is an excellent example of the benefits that can be secured when companies engage with stakeholders in helping to achieve safe drinking water.

Incidents in 2005 The companies in the Thames region notified the Inspectorate of 79 events during 2005. The Inspectorate classified 12 as ‘incidents’ requiring a comprehensive report from the company and a full investigation by the Inspectorate, as compared to nine in 2004.

Table 3.5.14 Water quality events in the region in 2005

Number of events notified Number classed as incidents

Sutton and East Surrey Water 3 3

Thames Water 57 5

Three Valleys Water 19 4

Region overall 79 12

A summary of the nature, cause and duration of each incident, along with details of the Inspectorate’s findings are set out in Annex 3. Most incidents were of relatively short duration and the company took action to inform and safeguard consumers and other stakeholders as appropriate.

Learning points from incidents assessed in the region in 2005 are highlighted by the following examples:

• In March 2005, consumers at four properties in the village of Clavering, Essex reported a creosote odour in their water supply. Three Valleys Water found that water which had been left standing in a section of main was supplied to consumers following repair of a burst. The Inspectorate concluded that the company communicated well with the ten consumers affected however the incident could have been avoided if the mains repair work had been planned more effectively by the company

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• Between April and July 2005, over 700 consumers in the High Wycombe area complained to Thames Water about discoloured water caused by a change in the supply arrangements. The company’s investigation found that water with a lower than normal dissolved oxygen content had released iron from the inner surface of the galvanised pipework in the local network. The Inspectorate’s investigation concluded that the incident could not have been easily predicted from the water quality models in use. The Inspectorate was very critical of the company for allowing the situation to continue for a protracted period before taking remedial action involving replacement of some customer supply pipes. The Inspectorate recommended the company considers in advance all possible implications of any future source changes or alterations to blending arrangements and always reacts promptly to customer reports of problems, making full use of its scientific and technical resources to safeguard supplies to consumers

• In November 2005, discoloured water was supplied to consumers in Edenbridge following the introduction of a new trunk main. The zone has a population of 3,750. Following overnight work to connect a new trunk main, Sutton and East Surrey received 26 consumers calls related to discoloured water. Air was introduced into the supply network during the recharge of the main. Flushing was insufficient to release all the entrained air and iron particles in the mains contributed further to the impact on consumers. The Inspectorate’s investigation of the incident found that the company did not have appropriate procedures for work on its trunk mains. The company has revised its procedures as a result of this incident.

The offence of supplying water unfit for human consumption is not currently under consideration by the Inspectorate in connection with any of the incidents that occurred in the region in 2005.

Technical audit activity in the region During 2005 the Inspectorate implemented a new decision making tool for prioritising its technical audit work. All critical components of the safe management of drinking water supplies (catchment, water treatment, distribution integrity and maintenance, sampling, analysis and reporting) are assigned a risk score based on company information (results of monitoring, incident assessment, previous audit findings, consumer complaints etc.). This tool generates a risk ranking for all relevant water company assets, procedures and practices. This enables inspectors to focus their technical audit work where it can be of greatest benefit.

As a result of this development, there is no longer an annual list of inspection tasks, instead technical audits are carried out as and when required throughout the year. Companies and laboratories will be audited less often if they adopt a proactive water safety plan approach to safeguarding water quality and ensure that their staff are well trained. Information on the key findings of the Inspectorate’s technical audit work in the region in 2005 is set out in table 3.5.15.

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Table 3.5.15 Summary of the Inspectorate technical audits in the region

Site name Audit topic Main findings from audit

Sutton and East Surrey Water

Sample audit trails. Audit of five chemical samples.

The company were required to make improvements to ensure that samples were preserved adequately prior to analysis. One matter related to the preparation of quality standards was remedied at the time of audit.

Thames Water

Fobney works. Site audit with specific focus on the disinfection process.

The company were required to make improvements to the maintenance and calibration of on-line monitors and equipment used for on site water quality tests. Improvements were also required to telemetry alarm levels on the site.

Mortimer works. Site audit with focus on process control.

The company were required to make improvements to site documentation and procedures and to investigate the cause of elevated iron and turbidity levels at this site. The treatment process controls have since been amended.

Swinford works. Site audit with focus on the disinfection process.

Satisfactory.

Blunsden service reservoir

Site audit with focus on integrity and sampling facilities.

Satisfactory.

Okus service reservoir.

Site audit with focus on integrity and sampling facilities.

The sampling arrangements required attention.

Audit of sampling arrangements

Audit of the collection and handling of compliance samples

The company were required to make improvements to the sample point at one of the service reservoirs visited.

Sample audit trails. Audit of nine chemical samples.

The company were required to make one improvement relating to the monitoring of analytical quality control.

Sample audit trails. Audit of three pesticide samples.

The company were required to make one improvement to the reporting limits of the analytical method.

continued

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Site name Audit topic Main findings from audit

Three Valleys Water

Sample audit trails. Audit of five chemical samples.

The company were required to make improvements to ensure that samples were preserved adequately prior to analysis and to ensure samples were taken at appropriate intervals.

Sample audit trails. Audit of one pesticide sample.

The company were required to make improvements to the reporting limits and quality control of the analytical method.

Local authority consultation Section 77 of the Water Act 1991 places a duty on local authorities to keep themselves informed about the quality of the public water supplies provided to premises in their area. In February 2006 the Chief Inspector contacted each local authority Environmental Health Service inviting their views on drinking water quality and the extent to which they are involved in local drinking water quality issues.

In the Thames region 55 out of a total of 82 local authorities gave their views:

• 54 indicated that they were satisfied with the quality of the public water supply

• 1 indicated that they were generally satisfied with the quality of the public water supply

• No local authorities indicated that that they were dissatisfied with the quality of the public water supply

• 46 indicated that they had regular contact with the local water company.

Comments by local authorities included:

• Good contact with Three Valleys Water, some problems with their call centre

• Delay of notifying us of disconnection of water supplies is sometimes a problem with Thames Water

• Some areas in South Oxfordshire suffer from low pressure on occasions

• It would be helpful to receive regular updates on programmes of work at treatment works.

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Thirty nine local authorities reported that they take samples of the public water supply, eighteen operate a planned sample programme and most collect a sample in response to a consumer complaint. One specifically indicated that they occasionally sample the water supply as part of their work in relation to the inspection of food production premises. Uttlesford District Council advised that they take samples at Stansted airport, which includes sampling from aircraft bowsers.

The Inspectorate has set up a formal link with the Chartered Institute of Environmental Health to identify and support training of local authority personnel on drinking water quality and regulation. A national steering group met in February 2006 to take this work forward and to provide regular feedback to the Inspectorate.

In partnership with the University of Surrey, the Inspectorate has established an internationally accredited postgraduate qualification in drinking water supply management and regulation (details in Annex 4). The modular style course can be studied on a full or part-time basis and covers the full range of knowledge required by professionals with responsibility for the ensuring the supply of safe drinking water. The course is available for the first time in 2006 and is commended to water companies and local authorities.

Consultation with health professionals The Health Protection Agency (HPA) is responsible for health surveillance in England and Wales. In England there are 34 Health Protection Units available to provide advice on health matters at a regional level, with 22 Health Boards fulfilling the same role in Wales.

In February 2006 the Chief Inspector contacted each Consultant in Communicable Disease Control and each Director of Public Health inviting them to comment on their involvement with drinking water matters during 2005. Information was received from 31 of these medical advisors and all but three of these had been involved in giving drinking water quality health advice during 2005. Typically health protection teams are responding to requests for advice in their area on eight occasions in any one year. The three most common reasons for providing health advice were:

• in response to a water quality incident

• in support of the local authority environmental health team

• a query about a specific substance that might be present in drinking water.

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In the Thames region nine medical advisors responded. They indicated that, on average, they would expect to be contacted for advice on eight occasions during a typical year. Seven indicated that they make use of the Inspectorate’s drinking water quality report and two of these reported it was a regularly used resource. Seven also indicated they made use of the Inspectorate’s website. Two indicated that they were not as aware of the Inspectorate’s role. Other comments included:

• An annual major incident report could be very useful

• It is a pity that the Environment Agency and water company boundaries do not match up

• The Inspectorate website could contain more information of use to health authorities. It is a most useful resource and improving it should be a priority

• More information on how Health Protection Units could work with the Inspectorate would be useful

• Details of the Inspectorate enquiry line and regional inspector contacts would be welcome.

The consultation exercise revealed that health professionals generally have a low awareness of the role and expertise of the Drinking Water Inspectorate suggesting that this topic is not being covered adequately by water companies in their routine liaison meetings with local health professionals. Companies are encouraged to invite the Principal Inspector for the region to participate regularly in local drinking water quality and health forums.

For further information on the Water Supply (Water Quality) Regulations 2000, or the microbiological and chemical parameters covered by the regulations please refer to the DWI website: http://www.dwi.gov.uk

If you have a need for more specific information than that on our website, please contact us on the DWI enquiry line: 020 7082 8024.

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Annex 1 Other sources of information There are two additional sources of information published this year, a CD and content published to the DWI website at http://www.dwi.gov.uk

Content of the CD The CD is supplied with this document in a folder.

Part 1 – Drinking water standards and science

Part 1 covers:

• How is drinking water quality regulated?

• The drinking water standards – European and National

• Drinking water science

• Drinking water research – completed in 2005 and ongoing.

Part 2 – Drinking water safety

This part presents:

• Chief Inspector’s statement

• An overview of water safety plans

• A review of the performance of the industry in 2005

• Individual summary tables of company performance.

Part 3 – Regional reports

There are six regional reports for England and one for Wales (In English and Welsh). The reports cover:

• Eastern region

• Midlands region

• Northern region

• Southern region

• Thames region

• Western region

• Wales.

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They summarise data from 2005 for the region under the following headings:

• Water sources

• Drinking water quality testing

• Drinking water quality results

• Consumer perceptions of drinking water

• Incidents in 2005

• Technical audit activity in the region

• Local authority consultation

• Consultation with health professionals.

Supplementary information In addition, published to the CD and DWI website are the following items.

Water company look-up tables

These summarise, by parameter, the results of water company tests taken in 2005. They provide information on:

• what was tested

• how many tests were performed

• the range of results of the tests

• how many failures were detected.

Incidents in England and Wales 2005

In order to assist the sharing of learning, the Inspectorate has published a compiled list of incidents that occurred in 2005 which illustrates the nature and cause of each incident and the main actions and findings of the Inspectorate. Regional extracts of this overall list are contained in each regional report (Annex 3).

Inspectorate’s website

The inspectorate has a website at http://www.dwi.gov.uk and in addition to the content described above, the following information can be found:

• The performance of the Inspectorate against its targets

• The prosecution record for the Inspectorate

• The details of where the Inspectorate has provided advice or made presentations.

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Annex 2 Glossary and description of standards

These definitions will assist the understanding of the Report where technical terms have been used.

Aggressive a term used to indicate that the water has a tendency to dissolve copper (and other metals) from the inner surface of a pipe or water fitting such as a tap.

Aesthetic associated with the senses of taste, smell and sight.

Alkali

a solution containing an excess of free hydroxyl ions, with a pH greater than seven.

AQC Analytical Quality Control is the method used to ensure that laboratory analysis methods are performing correctly.

Aquifer water-containing underground strata.

Atrazine a chlorotriazine herbicide registered for use in forestry and in sweetcorn.

Authorised Departure authorisation for a water company to temporarily supply water exceeding a drinking water standard, granted by the Authorities only when there is no risk to human health.

Bulk supply water supplied in bulk, usually in treated form, from one water company to another.

Chloramine a substance formed by reaction between chlorine and ammonia, used as a disinfectant in distribution systems because of its long lasting properties compared to chlorine.

Chloramination the process of generating a chloramine disinfectant residual in water leaving a treatment works.

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Chlorine residual the small amount of chlorine or chloramines present in drinking water to maintain its quality as it passes through the water company’s network of pipes and household plumbing.

Chlorotoluron a phenylurea herbicide registered for use in cereals.

Coagulation a process employed during drinking water treatment to assist in the removal of particulate matter.

Compound a compound consists of two or more elements in chemical combination.

Communication pipe the connection from the water main to the consumer property boundary (normally at the outside stop tap).

Compliance assessment a comparison made by the Inspectorate of data gathered by water companies against standards and other regulatory requirements.

Concessionary supplies historical free supplies of water for a householder, established when a company wanted to lay mains across land and the landowner might agree, subject to a permission, to take a supply of water from the main.

Contact tank a tank, normally situated on a treatment works site, which forms part of the disinfection process. A disinfectant chemical (normally chlorine) is dosing into the water as it flows into the tank. The period of time that the water takes to flow through the tank allows sufficient ‘contact’ time for the chemical to kill or deactivate any viruses or pathogenic organisms that may be present in the water.

Contravention a breach of a regulatory requirement.

Cryptosporidium a protozoan parasite.

Determination an analysis for a specific parameter.

Dicamba a benzoic acid herbicide registered for use in cereals and grass.

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Distribution systems a water company’s network of mains, pipes, pumping stations and service reservoirs through which treated water is conveyed to consumers.

Diuron a phenylurea herbicide registered for amenity use.

Drinking water standards the prescribed concentrations or values listed in Regulations.

EC Drinking Water Directive Council Directive 98/83/EC December 1998 – setting out drinking water standards to be applied in member states.

Enforcement action the means, as set out in the Water Act 1989 and consolidated into the Water Industry Act 1991, by which the Secretary of State requires a water company to comply with certain regulatory requirements.

Environment Agency the Environment Agency is responsible for maintaining or improving the quality of fresh, marine, surface and underground water in England and Wales.

Epidemiology a process of studying the distribution of cases of disease within a population in relation to exposure to possible sources of the infection, with a view to establishing the actual source of the infection.

Epoxy resin re-lining a rehabilitation process in which a cleaned section of iron water main is sprayed with a mixture of epoxy resin and hardener to produce a thin but strong coating of material on the inside of the main.

Exceedence synonym for contravention or breach (see above).

Filtration the separation of suspended particulate matter from a fluid.

Granular activated carbon an adsorbent filtration media used to remove trace organic compounds from water.

Groundwater water from aquifers or other underground sources.

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Improvement programmes water company improvement works, these are legally binding on the company and each programme will remedy an actual or potential breach of a drinking water standard within a specified time period.

Incident an event affecting or threatening to affect drinking water quality.

Indicator parameter something that is measured to check that control measures, such as water treatment, are working effectively.

Indicator organism an organism which indicates the presence of contamination and hence the possible presence of pathogens.

Information Letter formal guidance to water companies given by the Inspectorate.

Inspectorate The Drinking Water Inspectorate.

Isoproturon a phenylurea herbicide registered for use in cereals.

Legal requirements the requirements as specified in the Water Act 1989, now consolidated into the Water Industry Act 1991, and the Regulations made under the Acts.

MCPA (4-chloro-2-methylphenoxy) acetic acid. An aryloxyalkanoic acid herbicide used for controlling broad-leaved weeds in grass or cereal crops.

MCPP 2-(4-chloro-2-methylphenoxy) propanoic acid. An aryloxyalkanoic acid herbicide used for controlling broad-leaved weeds in grass or cereal crops. Commonly referred to as Mecoprop.

Mecoprop see MCPP.

Mean zonal compliance % a measure of compliance with drinking water standards introduced by the Inspectorate in 2004 see zonal percentage compliance.

Microbiological associated with the study of microbes.

m3/d cubic metre per day.

mg/l milligram per litre (one thousandth of a gram per litre).

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Ml/d megalitre per day (one Ml/d is equivalent to 1,000 m3/d, or to 220,000 gallon/d).

µg/l microgram per litre (one millionth of a gram per litre).

New regulations the Water Supply (Water Quality) Regulations 2000 in England; the Water Supply (Water Quality) Regulations 2001 in Wales.

Notice of Intention to make a Final Order

a necessary precursor to the issue of an Enforcement Order which must be advertised with a minimum of 28 days being allowed for representations or objections to the proposed Order.

Ofwat the water industry’s economic regulator.

Oocyst the resistant form in which Cryptosporidium occurs in the environment, and which is capable of causing infection.

Organoleptic characteristics of a substance as detected by our senses, for example taste, odour or colour.

Outbreak Control Team (OCT) a team set up to investigate possible waterborne outbreaks of cryptosporidiosis, comprising members of the medical profession, as well as representatives of relevant local authorities and water companies.

Ozone process (ozonation) the application of ozone gas in drinking water treatment.

Parameters the substances, organisms and properties listed in Schedule 2 and regulation 3 of the Regulations. Parameter definitions can be found further on in this annex.

Pathogen an organism which can infect humans and cause disease.

PCV see ‘Prescribed concentration or value’.

Periodic review the economic regulator’s process of setting water prices.

Pesticides any fungicide, herbicide or insecticide or related product (excluding medicines) used for the control of pests or diseases.

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Phosphate dosing treatment of water that results in a protective film building up on the inside of pipes minimizing the likelihood of lead being present in drinking water supplied through lead pipes.

Plumbosolvency the tendency for lead to dissolve in water.

Pre- and post- renovation assessment (PPRA)

a programme of assessment before and after mains renovation to demonstrate justification for the work, and the improvements achieved by the renovation.

Prescribed concentration or value (PCV)

the numerical value assigned to drinking water standards defining the maximal or minimal legal concentration or value of a parameter.

Private supplies water taken from private sources or supplied by non-licensed suppliers; supplies of water provided otherwise than by a statutorily appointed water undertaker.

Protozoan parasites a single cell organism that can only survive by infecting a host.

Public Register drinking water quality information made available to the public by water companies as required by regulations.

Public supplies water supplied by a company licensed for that purpose.

Raw water water prior to receiving treatment for the purpose of drinking.

Regulations The Water Supply (Water Quality) Regulations 2000 (England), 2001 (Wales).

Regulatory requirements see ‘Legal requirements’.

Remedial action action taken to improve a situation.

Residual disinfectant the small amount of chlorine or chloramines present in drinking water to maintain its quality as it passes through the water company’s network of pipes and household plumbing.

Secretary of State Secretary of State for Environment, Food & Rural Affairs.

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Service connection connection between the water company main to a consumer’s property.

Service pipe the service pipe is the pipe that connects the consumers property to the water company main. It comprises two part – the communication pipe which is the connection from the water main to the consumer’s property boundary (normally at the outside stop tap) and the supply pipe which runs from the boundary of the property to the consumer's inside stop tap.

Service reservoir a water tower, tank or other reservoir used for the storage of treated water within the distribution system.

Simazine a chlorotriazine herbicide registered for use in a range of agricultural and horticultural crops.

Springs groundwater appearing at the surface at the outcrop of the junction of a permeable with an impermeable stratum.

Statement of intent formal written acknowledgement from a water company about action it plans to take to address an actual or potential regulatory breach.

Supply pipe pipe connecting between the boundary of a consumer’s property to the inside stop tap.

Supply point a point other than a consumer’s tap authorised for the taking of samples for compliance with the Regulations.

Surface water untreated water from rivers, impounding reservoirs or other surface water source.

Technical audit the means of checking that water companies are complying with their statutory obligations.

Time of supply the moment when water passes from the water company’s pipework into a consumer’s pipework.

Trietazine a chlorotriazine herbicide – no longer registered for use in the UK.

Toxicology the study of the health effects of substances.

Treated water water treated for use for domestic purposes as defined in the Regulations.

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Undertaking a legally binding programme of work to take appropriate steps to secure or restore compliance with regulatory duties; given by a water company to the Secretary of State for the purposes of section 19(1)(b) of the Water Industry Act 1991.

Water supply zone a pre-defined area of supply for establishing sampling frequencies, compliance with standards and information to be made publicly available.

WHO World Health Organisation.

Wholesome/Wholesomeness a legal concept of water quality which is defined by reference to standards and other requirements set out in the Regulations.

WRc Water Research Centre (1989) plc and/or, as the context may require, its predecessor body.

Zonal compliance % the percentage of results for a specific parameter which complied with the PCV – the mean zonal percentage compliance is the average of the zonal percentage compliances of every one of a company's zones, can also be applied to all zones in a region or a country.

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Drinking water standards Microbiological standards

To protect public health there are microbiological standards which have to be met at each treatment works and treated water service reservoir or tower. Microbiological tests are also undertaken on consumer tap samples. The significance of individual test results for each microbiological parameter at each location varies and a single positive result does not necessarily mean that water is unsafe to drink. Other information is required to assess water safety. Each of the standards is listed below:

Parameter Description Standard

Escherichia coli and Enterococci

are bacteria present in the gut of warm blooded animals. They should not be present in drinking water and, if present, immediate action is required to identify and remove any source of faecal contamination that is found.

0 per 100ml

Cryptosporidium is a parasite that causes severe gastroenteritis and can survive disinfection. In the UK continuous monitoring is undertaken at works classified by the company as being at significant risk. The treatment standard for these works is <1 oocyst per 10 litres.

<1 oocyst per 10 litres

Clostridium perfringens

is a spore forming bacterium that is present in the gut of warm blooded animals. The spores can survive disinfection. The presence of spores in drinking water indicates historic contamination that requires investigation.

0 per 100ml

Coliform bacteria are widely distributed in the environment often as a result of human or animal activity but some grow on plant matter. Their presence in a water supply indicates a need to investigate the integrity of the water supply system.

0 per 100ml

Colony Counts are general techniques for detecting a wide range of bacteria, the types and numbers being dependent on the conditions of the test. These counts, if done regularly, can help to inform water management but they have no direct health significance.

‘no abnormal change’

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European health-based chemical standards

European health based standards for chemicals are set with a wide margin of safety on the basis of a life time’s consumption of water and taking into account the amounts present in food. Just because a standard has been set for a substance does not mean that it is present in drinking water. The vast majority of the regulated chemicals are never found in drinking water in England and Wales. Others occur only in very specific or local circumstances which are described below.

Parameter Description Standard

Acrylamide monomer is not normally found in drinking water. It is produced in the manufacture of polyacrylamides occasionally used in water treatment. Its presence in drinking water is limited by control of the product specification.

0.1 µg/l

Antimony is rarely found in drinking water. Trace amounts can be derived from brass tap fittings and solders.

5 µg/l

Arsenic occurs naturally in only a few sources of groundwater. Specific water treatment is required to remove it.

10 µg/l

Benzene is present in petrol. It is not found in drinking water but it can migrate through underground plastic water pipes if petrol is spilt in the vicinity. Some bottled waters and soft drinks which include sodium benzoate as an ingredient have been reported as containing benzene.

1 µg/l

Benzo(a)pyrene (BaP)

is one of several compounds known as polycyclic aromatic hydrocarbons (PAHs). Their source in drinking water is as a result of deterioration of coal tar which many years ago was used to line water pipes. Due to extensive water mains refurbishment and renewal it is now rare to detect this substance in drinking water.

0.01 µg/l

Boron in surface water sources comes from industrial discharges or from detergents in treated sewage effluents. The very low concentrations found in some drinking waters are not a concern to public health.

1 mg/l

Bromate can be formed during disinfection of drinking water through a reaction between naturally occurring bromide and strong oxidants (usually ozone). It may be generated in the manufacture of sodium hypochlorite disinfectant. Exceptionally, groundwater beneath an industrial site can become contaminated with bromate.

10 µg/l

continued

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Parameter Description Standard

Cadmium is rarely detected in drinking water and trace amounts are usually due to dissolution of impurities from plumbing fittings.

5 µg/l

Chromium is not present in drinking water. 50 µg/l

Copper in drinking water comes mostly from copper pipes and fittings in households. In general water sources are not aggressive towards copper but problems very occasionally occur on new housing estates. These ‘blue water’ events can be avoided by good plumbing practices.

2 mg/l

Cyanide is not present in drinking water. 50 µg/l 1,2-Dicholoroethane is a solvent that may be found in groundwater in

the vicinity of industrial sites. Where necessary it can be removed by special water treatment.

3 µg/l

Epichlorhydrin can be found in trace amounts in polyamine water treatment chemicals. Its presence in drinking water is limited by control of the product specification.

0.1 µg/l

Fluoride occurs naturally in many water sources especially groundwater. It cannot be removed by conventional water treatment so high levels must be reduced by blending with another low fluoride water source. Some water companies are required by the local health authority to fluoridate water supplies as a protection against tooth decay. The drinking water standard ensures levels are safe in either circumstance. Fluoridation of water is a Department of Health policy.

1.5 mg/l

Lead very occasionally occurs naturally in raw waters but the usual reason for its presence in drinking water is plumbing in older properties. If the water supply has a tendency to dissolve lead then water companies treat the water to reduce consumer exposure. The permanent remedy is for householders to remove lead pipes and fittings.

25 µg/l but 10 µg/l will

apply from 2013 onwards.

Mercury is not found in sources of drinking water. 1 µg/l Nickel occurs naturally in some groundwater and where

necessary special treatment can be installed to remove it. Another source of nickel in drinking water is the coatings on modern taps and other plumbing fittings.

20 µg/l

Nitrate occurs naturally in all source waters although higher concentrations tend to occur where fertilisers are used on the land. Nitrate can be removed by ion exchange water treatment or through blending with other low nitrate sources.

50 mg/l

continued

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Parameter Description Standard

Nitrite is sometimes produced as a by-product when chloramine is used as the essential residual disinfectant in a public water supply. Chloramine is the residual disinfectant of choice in large distributions systems because it is more stable and long lasting. Careful operation of the disinfection process ensures levels of nitrite are kept below the standard.

0.5 mg/l

Pesticides – organochlorine compounds (aldrin, dieldrin, heptachlor, heptachlor epoxide)

are no longer used in the UK because they are persistent in the environment. They are not found in drinking water.

0.03 µg/l for each compound

Pesticides – other than organochlorine compounds

is a diverse and large group of organic compounds used as weed-killers, insecticides and fungicides. Many water sources contain traces of one or more pesticide as a result of both agricultural and non-agricultural uses mainly on crops and for weed control on highways and in gardens. Where needed, water companies have installed water treatment (activated carbon and ozone) so that pesticides are not found in drinking water. Water companies must test for those pesticides used widely in their area of supply. Pesticide monitoring thus varies according to risk.

0.1 µg/l for each individual

substance and 0.5 µg/l for the

total of all pesticides

Polycyclic aromatic hydrocarbons (PAHs)

is a group name for several substances present in petroleum based products such as coal tar. (see Benzo(a)pyrene listed above for more information).

0.1 µg/l for the sum of all the

substances

Selenium is an essential element and a necessary dietary component. Amounts in drinking water are usually well below the standard.

10 µg/l

Tetrachloroethane and Trichloroethene

are solvents that may occur in groundwater in the vicinity of industrial sites. Where necessary they are removed by specialist treatment.

10 µg/l for the sum of both substances

Trihalomethanes are formed during disinfection of water by a reaction between chlorine and naturally occurring organic substances. Their production is minimised by good operational practice.

100 µg/l

Vinyl chloride may be present in plastic pipes as a residual of the manufacturing process of polyvinyl chloride (PVC) water pipes. Its presence in drinking water is controlled by product specification.

0.5 µg/l

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National chemical and physical standards The European Drinking Water Directive recognises the importance of maintaining a high quality of drinking water and for this reason several standards set in the original 1980 Drinking Water Directive (but not the 1998 Drinking Water Directive) have been continued in the form of National Standards. Most of the standards address levels that make the water unacceptable to consumers on the grounds of taste, odour or appearance.

Parameter Description Standard

Aluminium occurs naturally in some source waters. It is removed from drinking water by conventional water treatment (coagulation and filtration). Aluminium sulphate and polyaluminium chloride may be used as water treatment chemicals at some water treatment works.

200 µg/l

Colour occurs naturally in upland water sources. It is removed by conventional water treatment.

20 mg/l on the Pt/Co scale

Iron is present naturally in many water sources. It is removed by water treatment. Some iron compounds are used as water treatment chemicals. However, the commonest source of iron in drinking water is corrosion of iron water mains.

200 µg/l

Manganese is present naturally in many sources and is usually removed during treatment

50 µg/l

Hydrogen Ion (pH)

gives an indication of the degree of acidity of the water. A pH of 7 is neutral; values below 7 are acidic and values above 7 are alkaline. A low pH water may result in pipe corrosion. This is corrected by adding an alkali during water treatment.

The standard is a range between

6.5 and 10.0

Odour and Taste can arise as a consequence of natural processes in surface waters particularly between late spring through to early autumn. Water treatment with activated carbon or ozone will remove these natural substances. The standard relates to the evaluations of a panel of people assessing samples in the laboratory.

Dilution Number 3 at 250C

Sodium is a component of common salt. It is present in seawater and brackish groundwater. Some treatment chemicals contain sodium. Concentrations in drinking water are extremely low but some water softeners can add significant amounts to drinking water where they are installed in homes or factories.

200 mg/l

Tetrachloromethane is a solvent that may occur in groundwater in the vicinity of industrial sites. Where necessary it is removed by specialist water treatment.

3 µg/l

Turbidity is a measure of the cloudiness of water. It can arise from disturbance of sediment within water mains.

4 NTU

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Additional monitoring parameters

In addition to the drinking water standards, water companies are required to test for additional indicator parameters to assist them with good water supply management and the control of drinking water quality. Some of these parameters have a European guide value set for the purpose of triggering an investigation of the water supply.

Parameter Description Guide value

Ammonium salts are naturally present in trace amounts in most waters. Their presence might indicate contamination of sanitary significance and they interfere with the operation of the disinfection process.

0.5 mg/l

Chloride is a component of common salt. It may occur in water naturally but it may also be present due to local use of de-icing salt or saline intrusion.

250 mg/l

Conductivity is a non specific measure of the amount of natural dissolved inorganic substances in source waters.

2500 µS/cm

Sulphate occurs naturally in all waters and cannot be removed by treatment.

250 mg/l

Total Indicative Dose is a measure of the effective dose of radiation the body will receive from consumption of the water. It is calculated only when screening values for gross alpha or gross beta (radiation) are exceeded.

0.10 mSv/year

Total Organic Carbon represents the total amount of organic matter present in water.

‘no abnormal change’

Tritium is a radioactive isotope of hydrogen. Discharges to the environment are strictly controlled and there is a national programme of monitoring surface waters.

100 Bq/l

Turbidity measurement is an important non-specific water quality control parameter at water treatment works because it can be monitored continuously on line and alarms set to alert operators to deterioration in raw water quality or the need to optimise water treatment.

1 NTU at treatment works

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Annex 3 Incidents in the Thames region in 2005 Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

07/01/2005 for 5 hours (TMS)

Putney Booster PS,London 33,181

Loss of supplies/poor pressure following a power failure

Company action: • Repaired faulty equipment

DWI comments and findings: • Did not notify Water Voice Thames.

09/03/2005 for 2 days (TVW)

Middle Street, Clavering, Essex 10

Taste/Odour (creosote/phenolic) associated with static water following burst main/valving

Company action: • Flushed mains • Sampled affected area • Issued a do not drink notice

DWI comments and findings: • Inadequate planning in repair of main • Thorough investigation into root cause • Good communication with consumers • May have supplied water unfit for human consumption.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

19/03/2005 for 18 days (TVW)

Well End, Borehamwood, Hertfordshire 75

Taste/Odour (musty) associated with a burst main

Company action: • Issued a do not drink notice • Provided bottled water on request • Left system to settle.

DWI comments and findings: • Supplied unwholesome water in breach of regulations • Supplied water unfit for human consumption • Company took prompt and appropriate action • No recommendations.

06/05/2005 for 9 weeks (TVW)

North Mymms works Hertfordshire 68,912

Evidence of chemical contamination (mecoprop herbicide) associated with a deterioration of the raw water

Company action: • Shut down treatment works • Rezoned area (brought in water from different source) • Replaced granular activated carbon at works • Requested short-term Authorised Departure whilst remedial works under way (due to increase in demand).

DWI comments and findings: • Supplied unwholesome water in breach of regulations • Recommendation made regarding the timeliness of the works shutdown.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

12/05/2005 for 20 weeks (TMS)

High Wycombe Buckinghamshire 9,775

Discolouration (brown) associated with a change in the source of the water

Company action: • The Company’s Customer Centre gave general advice for discoloured water. More than 700 consumers contacted the company to report discoloured water or request bottled water • As of 16/06/05 the company returned the affected area to water supplied from primarily from Bourne End WTW, excepting where hot weather required some support from Dorney WTW • Mill End WTW was brought back in to supply on 22/06/05 (after clear sample results) to cope with the increased demand in the area • The orthophosphoric acid dose at Bourne End works was increased gradually from 1.0 mg/l to 1.2 and finally to 1.5 mg/l on 22/06/05. This was a temporary change to aid in reducing the iron release from the affected pipe work • The company undertook more than 300 surveys, replaced at least 271 communication pipes and 162 supply pipes with 131 properties having had both lots of pipe work replaced • All properties, which had their pipe work replaced, had sampling carried out to confirm that the situation has been resolved • Four cartridge filters have been fitted to properties with particularly elevated iron levels due to long service pipework • A letter drop was carried out to inform all consumers in the area immediately affected with a further letter drop to 1700 properties in the affected zone not covered by the initial letter drops • The company provided bottled water and were still providing 371 properties with alternative supplies in June 2005 dropping to 198 in July 2005 before the company planned removal of the provision through direct contact and sampling • Once notified communication maintained throughout with external authorities, including the MP & councillors.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

• An online oxygen monitor was installed at Dorney WTW and a further one is due to be installed at Hedsor Service Reservoir to monitor the situation • Two pipe rigs have been constructed at Dorney WTW to determine the mechanism of iron release from customer’s iron pipes and confirm or reject the suspected cause of low dissolved oxygen • As a way forward, a temporary engineering solution is being sought by the company at Hedsor and options for a long term solution at Dorney are being developed.

DWI comments and findings: • Concluded that it is unlikely that the company could have used existing water quality models to predict this incident, however research following the incident did identify the change in dissolved oxygen content as the most likely cause • Critical of the time that the company permitted this situation to continue • Recommended the company ensures sufficient research is carried out prior to any change of source or blending of water and that where unforeseen adverse effects occur that the company investigates the cause as soon as possible, including the early use of expert scientific and technical knowledge to minimise the impact on consumer’s supplies • Recommend that the company notifies the relevant bodies as required by the Water Undertakers (Information) Direction 2004 and regulation 35(8) of the Water Supply (Water Quality) Regulations 2000 as soon as may be after the event has come to the undertakers attention.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

22/07/2005 for 5 days (TMS)

Westonfield, Albury, Guildford, Surrey 87

Taste and Odour (petrol) associated with planned work by an approved contractor

Company action: • Flushed mains • Opened the closed valve that was the root cause of the incident • Provided bottled water on request.

DWI comments and findings: • Two factors in combination contributed to this incident: a) the valve was closed at the Monument which will have resulted in a stagnant length of main, and b) the connection of the new main at the apex of Weston Fields caused disturbance of the stagnant part of the main, resulting in the complaint from a consumer and the increase in measured iron, manganese, turbidity, polycyclic aromatic hydrocarbons and dissolved hydrocarbons. The presence of the taste and odour was confirmed by the company Water Quality Technician at each property where he was able to gain access up to number 23 on one side of the road • Recommended that where the company has detected a failure of a particular parameter that the subsequent re-samples be tested for the parameter that initially failed • Recommended that the company ensures that prior to any work the network is in an appropriate configuration for such work to proceed.

16/08/2005 for 4 days (TMS)

Aldbourne (SN8) Wiltshire 350 (approx)

Taste and Odour (petrol) following planned work by company staff

Company action: • Provided bottled water on request • Flushed mains • Sampled affected area • Reversed rezoning.

DWI comments and findings: • Assessment Ongoing.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

26/08/2005 for 2 days (TMS)

Hurtwood & Abinger, Surrey 6,500

Loss of supplies/poor pressure following a power failure

Company action: • Provided an alternative supply by tanker/bowser • Sampled affected area

DWI comments and findings: • Telemetry failure due to a loss of power and back up telephone line also failed. Delay in company realising communication with the site had been lost • Generator out of service for nine days prior to incident and backup only available following incident • Inadequate contingency planning. Recommended that the company has a temporary replacement of standby generators where there is no possibility of acquiring a standby generator and/or restoring power to the site before the supply to consumers is impacted.

17/10/2005 for 3 days (SES)

Langley Park Reservoir 10

Evidence of microbiological contamination (E.coli and coliform bacteria) as a result of inadequate sampling arrangements at the site

Company action: • The sampling discharge lines have now been changed to prevent this occurring again • Lab investigation into results supported analysis was correct • Consultant Microbiologist contacted for advice.

DWI comments and findings: • There was contamination of the regulatory sample taken on 13 October 2005 from Langley Park Reservoir no.2 as a result of poor sampling arrangements. Improvement work completed on site.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

24/11/2005 for 25 hours (SES)

Edenbridge, Kent 3,750

Discolouration (brown) associated with planned work by company staff

Company action: • Opened hydrant at the downstream end of new main and established that the mains supply was aerated. Left the hydrant running for a period of almost 4 hours until it ran clear • Company staff progressively flushed the trunk mains that run through the area affected in order to remove any trapped air • Sampled four properties of consumers who had complained • Customers who contacted the company were advised to continue to flush the water from their taps until it became clear • Where requested, bottled water was provided • Reviewed sensitive customer register, contacted consumers by telephone to establish what assistance was needed.

DWI comments and findings: • The existing procedures are not sufficiently explicit about how they should be applied to trunk mains, when the connection works typically result in the main being put into full service directly (such as in this case) • Trunk main works will now be clearly described in the company mains commissioning procedure of the Network Operating Manual such that the likelihood of a similar event occurring in the future is minimised • In the interim, until the new procedure is in place, all works on mains greater than 6inches /150mm diameter where they affect the existing network will be referred to the Distribution Manager.

continued

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Date and duration (Company)

Area and estimate of population affected

Nature and cause of the incident

Main actions and findings from the Inspectorate investigation

09/12/2005 15 hours (SES)

Cold Harbour Lane, Westcott nr. Dorking, Surrey 2,030

Discolouration (brown) associated with a burst main

Company action: • Flushed mains • Provided bottled water on request.

DWI comments and findings: • Company acted appropriately in response to mains burst.

15/12/2005 for 9 days (TVW)

Runley Wood Greensand works, Luton, 4,750

Evidence of chemical contamination (bromate) in final water from works, as a result of elevated bromide level in the salt used for on site generation of chlorine

Company action: • Resamples contained elevated bromide, works shut down • Company investigation established that the bromide levels in the salt used in the process of chlorine generation was not appropriate because of the high chlorine dose used at the works • Salt changed for a lower bromide concentration • Operating procedures were revised to ensure only treatment chemicals with low bromide concentration are now used at this site.

DWI comments and findings: • Initial findings indicate that the change of salt to one which had a higher bromide concentration was inappropriate for this works. • Assessment Ongoing.

Note: A complete table of incidents in England and Wales in 2005 can be found on the CD in the folder. It is named Incidents in England and Wales 2005.pdf. It is also available on the DWI website at http://www.dwi.gov.uk

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Annex 4 Water regulation and management MSc CEHE – the Centre for Environmental Health Engineering – is located within the School of Engineering at the University of Surrey, Guildford. The Centre consists of a multidisciplinary team of engineers and scientists and provides a high level of academic resources for teaching and for research activities. CEHE has well-developed links with the UK water industry, regulators, international water groups, environmental bodies and relief agencies.

The CEHE programmes address key issues of management and engineering associated with the water cycle: water and wastewater treatment, water resources management, waste management and regulation. The MSc multidisciplinary programme, ‘Water and Environmental Engineering’, has been run by the Centre since 1992 and has a proven reputation throughout the world. It has been regularly updated to take account of new developments and to meet market needs. The most recent change is the addition of a Water Regulation and Management MSc, a variation of the Water and Environmental Engineering MSc with a strong focus on all aspects of regulating the production and distribution of safe drinking water. The new programme is supported by the Drinking Water Inspectorate, it is modular and can be studied on a full-time basis over one year or on a part-time basis over a minimum of two years.

Candidates should be graduates with a good science or engineering honours degree, or practitioners with suitable vocational qualifications and relevant experience in science or engineering.

Additionally, selected modules can be studied by those wishing to acquire particular expertise in one aspect of the modern practice of water and environmental engineering. The modules provide an excellent opportunity for mid career refreshment of the skills and knowledge of water managers.

The career histories and career development of students of the CEHE programme has shown that it is highly successful with many now being responsible for water supply management or in influential water policy and regulation roles around the world.

The awards Postgraduate Certificate 4 modules (60 credits)

Postgraduate Diploma 8 modules (120 credits)

Master of Science 8 modules and a project dissertation (180 credits)

Each module carries 15 credits and the dissertation 60 credits.

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The modules

Currently the Master of Science and Postgraduate Diploma programmes offer seven compulsory modules and 3 optional modules.

Compulsory modules

Environmental health

• Water-related diseases

• Epidemiology of waterborne diseases

• Pathogens: bacteria, viruses and parasites

• Water quality control principles and practice

• Identification of bacteria

• Sanitary bacteriology

• Chemical analysis

• Principles of toxicology.

Water treatment

• Need for water treatment

• Types of raw water source

• Management of reservoirs

• Water treatment systems

• Developing world systems

• Particle removal

• Specialised treatment: desalination, reverse osmosis

• Disinfection

• Distribution systems

• Operational management.

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Wastewater treatment and sewerage

• Wastewater quality

• Wastewater treatment and health

• Wastewater treatment unit processes

• Activated sludge and percolating filter treatment

• Waste stabilisation ponds

• Tertiary processes

• Kinetics of treatment

• Design and management of wastewater treatment systems

• Sewerage design and construction.

Pollution control and waste management

• Conventional industrial wastewater treatment

• Advanced industrial wastewater treatment

• Sludge treatment and disposal

• Ultimate disposal of solid and hazardous waste

• Contaminated land assessment and remediation technologies

• Waste minimisation/life cycle assessment

• European legislation on waste management.

Applied chemistry and microbiology

• Chemical concepts: moles, equivalents, units, definitions

• Aqueous chemistry

• Hardness and alkalinity

• Kinetics and equilibria

• Electrochemistry

• Process principles: mixing, mass balance, mass transfer and reactor theory

• Microbiology classification and terminology

• Biochemical pathways

• Growth and death of micro-organisms

• Isolation of bacteria.

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Regulation and management I

• Project planning – feasibility/framework

• Project management

• Finance planning and management

• Information management

• International water quality guidelines

• European legislation and standards

• Water company technical audits

• Environmental law

• Pollution regulation

• Analytical quality control

• Case studies

• Environmental impact assessment.

Regulation and management II

• UK industry arrangements including primary and secondary legislation and aspects such as competition, self regulation

• UK finance arrangements

• Operational and regulatory drinking water quality monitoring (including AQC)

• Planning sampling programmes/sampling requirements

• Reporting

• Communication

• Drinking water safety plans (risk assessment, risk management, validation, verification, communication)

• Inspection/technical audit (check lists, in practice, inspection reports, required skills).

Drinking water safety plans

• Catchment, treatment and distribution (hazard identification)

• Hazards and controls

• Risk assessment and risk management

• Design (pipes, reservoirs, pumps etc)

• Distribution operation and maintenance

• Asset management

• Causes of degradation of water quality post treatment

• Water systems within buildings

• Consumer protection and acceptability

• Reporting (public/government).

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Optional modules

Water surveillance

• Principles of surveillance

• River processes

• Water quality monitoring

• Remote sensing

• Analysis and interpretation of aerial photography

• Digital image processing and interpretation

• Land use and impact upon water quality

• Biological monitoring

• Land cover classification

• Digital elevation models

• Interaction matrices

• Geographical information systems (GIS).

Groundwater control, modelling and contamination

• Sources of drinking water

• Groundwater origins

• Geological considerations

• Common extraction contaminants: types, sources and method of transport

• Seepage theory and physical modelling

• Numerical modelling of single and multi-phase flow

• Groundwater control techniques and strategies

• Vulnerability and hazard assessment.

Industrial project

Students on the MSc programme would be required to apply knowledge gained on the programme and to critically evaluate technological approaches and the management strategies adopted in industry. This would involve a placement with a water supplier or regulator of approximately one week.

The Industrial Project will provide a unique opportunity to use newly acquired skills and knowledge in the working industrial environment.

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Dissertation

The project forms the basis for a concentrated study of a topic and, in addition to a comprehensive literature survey, may include:

• field studies

• computer-based studies

• laboratory investigations

• a combination of these activities

Some projects are University-based; others may involve collaboration with, and work in, industry. Due to their nature, some projects may require gathering information, conducting research, and/or collecting data from overseas countries. All students must produce a formal dissertation proposal for the approval of the Programme Director. The dissertation based on the project represents a total of 60 credits (600 hours of student workload). It must be on a water or environmental topic approved by the Programme Director and supervised by a member of the Board of Examiners solely, or jointly with a specialised industrial supervisor.

Application process Anyone wishing to apply for a place on the MSc programme can either:

• visit the website http://www.surrey.ac.uk/eng/pg/cehe where all the information about the Masters Programme is given.

• take the link to ‘Contact Details’ and an application form can be downloaded.

Or alternatively:

• access the website at http://www.surrey.ac.uk/postgraduates and take the link to ‘Order Prospectus’. There is an online form to fill in, after which details and an application form will be supplied.

Note: It is helpful when returning an application if prospective students would enclose a copy of their undergraduate degree certificate.

The form and accompanying details should be sent to:

Postgraduate Registry University of Surrey Guildford Surrey GU2 7XH

Applications are required by mid-July for places in the academic year starting September.

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Drinking water 2005Part 3 Thames region

A report by the Chief InspectorDrinking Water Inspectorate

Drinking Water Inspectorate | 55, Whitehall | London | SW1A 2EY | Tel: 0207 082 8024

http://www.dwi.gov.uk