National Institute of Environmental Health, Budapest

1st Task Force Meeting Extr/Hlth, Rome

April 21-21, 2008

Drinking-water outbreak due to karst water flooding -

environmental-health aspect

Case study

Sources of drinking water in Hungary

Ground water extraction 94,1 %

•bank filtration 39,4 %•karst water 11,2 %•not protected groundwater 2,6 %•protected (deep) well 40,1 %• thermal and mineral water < 1 %

Consumer:

• 180000 resident

• 35000-42000 m3 human consumption

• 4 water source

Water Source –karst water:

• Sensitive

• Low operational costs

• High quality drinking water

Drinking water supply of the city Miskolc

0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

kémiai bakteriológiai biológiai részletes

mintaszám kifogásolt mintaszám

Inspection by self-monitoring (A) and inspection authorities (B)

Number of samplesNumber of samples and objected samplesobjected samples

Drinking water quality test in 2006

0

25

50

75

100

125

150

175

200

225

250

275

300

kémiai bakteriológiai biológiai részletes

mintaszám kifogásolt mintaszám

AA BB

• Precipitation between 23 May and 6 June 2006215,8 mm (16,8 million m3 )– accumulated water on the surface 2,5-3 million m3

• Water catchment area of the wells: 76 km2

Extrem weather conditions

• 02/6 Szinva and Garadna creeks flooded

• 03/6 Public Health Service received complaint from public that “tap water is troubled, murky” in western part of the city

• 06/6 Official laboratory test results were negative

• 08/6 at 11 am, NPHMOS receives notification that waterwork operator sample (taken on 06/6 subsequent to holiday) contains bacterial contamination, but not in western part of city

• 08/6 at 1 pm Department of Epidemiology gets report from GPs of mass complaints of diarrhoea (University Town section of city)

• sanitary-epidemic measures are taken (onsite inspection, samples taken by authorities)

• 08/6 at 11 pm Public Health Service issues briefing to public

Events

Events at the waterworks

• turbidity begins to rise on Saturday, 3 June, at 12 noon

• at 2 pm the turbidity reaches the limit value and extraction from the well is stopped

• at 8 pm the turbidity has dropped to below 10 NTU and the well is re-connected to the mains. The turbidity value is 9-10 NTU and the water is chlorinated at 0.4 mg/L

• turbidity value begins to rise again, and on Sunday morning at 5:40 am the well is disconnected from the Miskolc water supply

• It was calculated that during the 9-10 hours, about 8,000-9,000 m of contaminated water was allowed into the mains.

• Most settlements along the drinking water protective area have sewage systems, and this is paradoxically an additional contamination hazard, because there is no conduit system built up to manage rainwater runoff (putting an overload on the sewage systems).

• Floodwaters racing through karst caves at high speed carry huge amounts of debris, river load which stir up the sediment in the cave gallery.

• There is no sedimentary tank to remove turbidity from the water at the waterworks (anyway not yet).

• Other potential sources of contamination:– 1. sinkholes, creek water– 2. sinkholes, lake water– 3. limestone canyon– 4. treated wastewater

Potential sources of contamination

Results of disclosed contamination

• bacteriological investigations found faecal contamination in the drinking water main

• protozoons (Cryptosporidium parvum and duodenal Giardia (non viable) were revealed

• heat-resistant Campylobacter (in a 5 litre water sample) were detected

• the biological/microscopic tests were found objectionable because of sedimentation, algae, and cyanobacteria

• chemical parameters were in complience with guideline values

Results of contamination studies

• Unconfirmed virus tests were positive for several viruses

Immunochromographic quick tests were positive for adenovirus and negative for rotavirus

IDEIA Norovirus Elisa tests were positive for Calcivirus genotypes GI and GII.

RT-PCR tests were negative for Calcivirus and Hepatitis A

Changes of E. coli and Enterococcus numbers in the raw water of the waterwork between June – November 2006

050

1001502002503003504004505005506002006.06.09

2006.06.16

2006.06.23

2006.06.30

2006.07.07

2006.07.14

2006.07.21

2006.07.28

2006.08.04

2006.08.11

2006.08.18

2006.08.25

2006.09.01

2006.09.08

2006.09.15

2006.09.22

2006.09.29

2006.10.06

2006.10.13

2006.10.20

2006.10.27

2006.11.03

2006.11.10

2006.11.17

szám

/100

ml

E. coli szám/ 100 ml Enterococcus szám/100 ml

Nu

mb

er/

10

0m

l

Immediate public health actions (I.)

• Organizing drinking water supply for the area affected (water in plastic bags, bottled water, and water-carrying tank trucks; mobile distribution sites with central depots in schools)

• Disinfection and rinsing out the mains that carried the contaminated water

• Daily bacteriological and chemical testing of water over entire area of city

• Increasing the initial chlorination level up to 2 g/m3 at the water feeding point (assuring at least 0.6-0.8 mg/L free chlorine for supplementary chlorination)

• Removing of the debris collected in the cave gallery and of the sludge believed to be infected (divers)

Inmediate public hygiene actions (II.)• Running the water from contaminated wells into ditches. The

water thus discharged had to be disinfected because it was let into the Hejő creek where many people bathed illegally because there was a heat wave.

• The water lost in the closedown had to be replaced from elsewhere. Water was transferred from another waterworks. At the transfer points there was daily bacteriological and chemical testing, and biological testing was conducted every three days.

• Giving information to the public. Daily media briefings were held and press releases were issued throughout this time. People were told not only about what had to be done in a situation of outbreak, but also how to help it come to a quick halt. Information was issued on the general features of a waterborne outbreak, and on how to avoid contact contamination. Water quality was also reported on an ongoing basis.

Public hygiene conditions that the operator needs to meet immediately and on longer term

on restarting the water works

• setting up a system for continuous monitoring of water quality and giving possibility to intervene immediately

• quick tests need to be introduced to check for contaminants common to karst water aquifers (ammonium, nitrites, chloride)

• a quick bacteriological test needs to be used for Coli bacteria (to determine individual limit values for untreated water

• laboratory tests have to be increased (daily tests for raw and treated water)

• the self-monitoring of the waterworks needs to be expanded

• a new set of Rules of Operation and of emergency plans has to be designed

• the most important drinking water protection tasks have to be planned out

Lessons

• It is necessary to have water treatment technologies in place that can manage emergency situations

• and to build up active means of protecting karst waters(control of the pollution sourcesontrol of the pollution sources, special special protection for caves and sinkholes protection for caves and sinkholes on DWPADWPA))

Thank you for your attention !

A csapadék mennyisége a Bükkben2006

0

10

20

30

40

50

60

70

80

90

100

2006

.05.

03

2006

.05.

05

2006

.05.

07

2006

.05.

09

2006

.05.

11

2006

.05.

13

2006

.05.

15

2006

.05.

17

2006

.05.

19

2006

.05.

21

2006

.05.

23

2006

.05.

25

2006

.05.

27

2006

.05.

29

2006

.05.

31

2006

.06.

02

2006

.06.

04

2006

.06.

06

2006

.06.

08

2006

.06.

10

2006

.06.

12

2006

.06.

14

2006

.06.

16

Utolsó adat 2006. június 17.

csa

pa

dé

k m

m-b

en

Miskolc-FelsőhámorMiskolc-ÓmassaNagyvisnyó-BánkútJávorkútRépáshuta

Precipitation 2006 Bükk MtsPrecipitation 2006 Bükk MtsP. Kovács

A singleA single pollution source causing the pollution source causing the pollution could not been identifiedpollution could not been identified