Information Letters

DWI Information Letter 16/2003

10 December 2003

To: Board Level Contacts of Water and Sewerage Companies in England and Wales

Dear Sir or Madam

The Water Supply (Water Quality) Regulations 2000 and the Water Supply (Water Quality) Regulations 2001 - Monitoring for Clostridium perfringens

Purpose

1. The purpose of this letter is to clarify the regulatory monitoring requirements for the Clostridium perfringens (including spores) parameter.

   Background

2. Council Directive 98/83/EC on the quality of water intended for human consumption (the Directive) specifies parametric values for microbiological parameters and chemical parameters which are mandatory and must be complied with. The Directive additionally specifies parametric values for indicator parameters which are non-mandatory values for monitoring and action is taken only if the exceedence is a risk to health.

3. The Directive specifies the circumstances when check or audit monitoring should be applied to a parameter. The purpose of check monitoring is regularly to provide information on the organoleptic and microbiological quality of the water supplied as well as information on the effectiveness of drinking water treatment. The purpose of audit monitoring is to provide the information necessary to determine whether or not all of the Directive’s parametric requirements are being complied with.

4. The Directive specifies Clostridium perfringens (including spores) as an Indicator Parameter. Its parametric value is 0 / 100 ml. A footnote to this parameter in Part C of the Directive states, inter alia, “this parameter need not be measured unless the water originates from or is influenced by surface water”.

5. This footnote is further clarified by Note 2, Annex II, Table A, Check monitoring, which states that “[Check monitoring is] necessary only if the water originates from or is influenced by surface water. In all other cases, the parameters are in the list for audit monitoring”.

6. The Directive requirement for audit monitoring for Clostridium perfringens (including spores) when check monitoring is not necessary, has not been transposed clearly into the Water Supply (Water Quality) Regulations 2000 and 2001 (the Regulations) because no audit monitoring frequency is specified for the parameter.

   Monitoring requirements under the Regulations

7. The Regulations (Schedule 3 Table 1) clearly require all water supplies where the water originates from or is influenced by surface water to be monitored at the check frequency specified in Schedule 3 Table 2 and Table 3.

8. Regulation 6(2) includes the Directive requirement for audit monitoring where check monitoring is not required. Where this is the case, water undertakers should monitor for the Clostridium perfringens (including spores) parameter at the audit frequencies for other parameters specified in Schedule 3 Table 2 and Table 3.

   Analysis for the Clostridium perfringens (including spores) parameter

9. The Inspectorate confirms that laboratories may use the methods specified in the Standing Committee of Analysts’ publication “The Microbiology of Drinking Water 2003 (Part 6)”. This is available on the Environment Agency’s website www.environment-agency.gov.uk.

   Future monitoring requirements

10. The United Kingdom has strongly supported both the conclusion of the European Advisory Group on Microbiology and the recommendation of the Microbiology Position Paper presented at the recent European Commission Water Quality Seminar on the future of the Directive that the Clostridium perfringens parameter should be deleted from the Directive, or at least be restricted to the audit frequency for all circumstances. The Commission is currently studying representations but it is unlikely that there will be an early change to any monitoring requirements.

    Enquiries

11. Any enquiries about the letter should be addressed to David Drury (telephone 020 7082 8018, david.drury@defra.gsi.gov.uk)

    Circulation

12. Copies of this letter are being sent to Pamela Taylor, Chief Executive, Water UK; Rodney Anderson, Water Supply and Regulation Division, Department for Environment, Food and Rural Affairs; June Milligan, Environment Division, The National Assembly for Wales; Tim Hooton, Drinking Water Quality Regulator for Scotland; Randal Scott, Drinking Water Inspectorate for Northern Ireland; and Rowena Tye, Office of Water Services.

13. This letter is being sent electronically to Board Level contacts. Please acknowledge receipt by e-mail to dwi.informationletters@defra.gsi.gov.uk. Hard copies are not being sent, but the letter may be freely copied.

    Yours sincerely

    

    Professor Jeni Colbourne
    Chief Inspector