Liz Stokle Senior Health Protection Nurse North East Health Protection Unit

1. Guidance for Responding to Drinking Water Quality Failures in theNorth East of England, March 2012 Liz Stokle Senior Health Protection Nurse North East Health Protection Unit

2. Responsibilities of Health Protection Unit Health Protection Agency Act 2004 HPA has a duty to protect the public from threats …infectious diseases and environmental hazards.  Following Notificationthe HPU with the local authority is to provide public health advice to the water company …pertinent to the local community affected. Significant threat to public health, the HPU has a duty to inform the appropriate Director of Public Health for the (PCT) responsible for the health of the population affected and then to work on mitigation.

3. Challenges for risk assessment Raw water abstraction Treated water Nature of problem failure – problems at WTW; burst main; discoloured water; loss of supply; failure of standard at any point in process

4. Challenges for risk assessment Raw water abstraction Treated water Nature of problem/failure Chemical and microbiological parameters

5. Microbiological parameters • Indicator Organisms • Coliforms • Faecal indicators: • E.Coli • Enterococci • C.Perfringens

6. Multiple variables • Coliforms • Alone or in conjunction with other organisms such as E.coli • Small numbers or high numbers

7. Other biological & chemical parameters • Cryptosporidium • Lead • Fluoride • Chlorine or lack of

8. Drinking water safety • “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 [or safe] to drink. • Other information is required to assess water safety.” • Drinking Water Safety -Guidance to health and water • Professionals (DWI/HPA December 2009)

9. Risk Assessment • Severity of consequences of the hazard: • Effect on human health not just • Meeting health based standards and indicator parameter values • The risk associated with the hazard needs to be considered in the context of the particular situation/circumstances

10. Contextual issues • Point of failure • Nature of failure • Size of population affected • Nature of population affected • Current awareness of GI illness

11. Challenges for protecting health of population • Interpreting the information/evidence • Risk assessment appropriate to context • Implementing proportionate response

12. Launch of document

13. Table 1: Response to notification from Northumbrian Water Limited or Hartlepool Water relating to failures of mains water samples or of events posing a threat to supply [

14. Reported failure – Mains Water • Domestic property – programmed sample result: • 42 presumptive coliforms • 0 E.coli • Free chlorine 0.16 mg/l • Total Chlorine 0.25 mg/l

16. Table 2 : Response to failures of private water samples

17. Reported failure – Private Water • Domestic property – programmed sample result: • 42 presumptive coliforms • 0 E.coli • Free chlorine ? • Total Chlorine ?

18. Private Water Supply

19. Coliforms in PWS *Where failure relates to coliforms without evidence of E.coli consider history of supply (where available) in relation to evidence that this result may suggest potential danger to human health e.g. management of supply not effective – in such cases a boil water notice may be warranted

20. Private Water Supplies

21. Shared guidance in NE