United Utilities Water Limited – Winwick Service Reservoir

Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)

Reference: UUT-2024-00001

Version Number: 1

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): United Utilities Water Limited, with registered number 02366678 (hereinafter called ‘the Company’).

Assets Affected:

• R020 Winwick Service Reservoir
• Y1521 Warrington Supply Zone
• Y1522 Wigan Supply Zone

Details of this Notice:

1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a regulation 28(1) report of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 1 October 2015, which states that there is or has been a significant risk of supplying water from Winwick Service Reservoir (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
2. Consequently, this Notice is served on the Company by the Inspectorate on behalf of the Secretary of State, under regulation 28(4) for the assets listed above, for risks associated with:

Description of Risk	Hazard/ Hazardous Event/ Parameter	Hazard I D
Failure of the integrity of the reservoir structure to prevent deterioration of water quality.	E.coli Coliforms Colony Counts Clostridium Enterococci	R020C002294254 R020C001294254 R020C007294254 R020C004A294254 R020C003294254

Table 1: Table of the hazards, hazardous events, and/or parameters covered by this Notice, including the Hazard I D numbers and the description of risks.

3. The Company are required to satisfy the following requirements.

The date given is that until or by which the requirements must be maintained or satisfied, as appropriate.

Requirements:

(a) To maintain the following measures for the period specified in each case:

1. Enhanced sampling at Winwick Service Reservoir (SR).
   Date: Ongoing for the duration of this Notice.
2. Maintenance and review of target chlorine residual and set points at Winwick SR.
   Date: Ongoing for the duration of this Notice.
3. Monitor coliforms, colony counts, Enterococci and chlorine residuals as part of the routine sampling programme within the downstream distribution system.
   Date: Ongoing for the duration of this Notice.
4. Management of flora and fauna at Winwick SR.
   Date: Ongoing for the duration of this Notice.
5. Site security, operational equipment checks and storage tank external inspection visits.
   Date: Ongoing for the duration of this Notice.
6. Manage Winwick SR levels based on demand and alarm set points.
   Date: Ongoing for the duration of this Notice.

(b) To review, revise or make operational the following measures, by the dates specified in each case:

1. Complete the inspection and cleaning of Winwick SR using the robust flood testing procedure to ensure maximum coverage of the tank roof and joints. Complete remedial work required on any compartment found to have ingress.
   Date: 31 December 2024.

(c) To audit whether the measures have been effective by the following means:

1. Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b), with updates as necessary, to include:
2. Enhanced monitoring for E. coli, coliforms, colony counts, Enterococci and Clostridium.
3. Full investigation of all detections of E. coli or coliforms or Enterococci or Clostridium, or of a step change in colony counts.
   Date: 31 October 2024.
4. Implement, and keep under continuous review, the audit strategy defined in measure (c)1.
   Date: Following completion of measure (c)1. onwards.

(d) Not to supply water for regulation 4(1) purposes from Winwick Service Reservoir, or not to so supply unless the specified conditions below are satisfied:

1. Not applicable.

(e) To provide the following information in the time and manner specified below to enable monitoring of progress towards the mitigation of the risks:

1. Provide a progress report annually.
   Date: by 31 January each year.
2. Provide the completed inspection report, demonstrating, with evidence, that Winwick SR has been fully inspected, cleaned, flood tested, and any required repairs have been completed, as defined in measure (b)1.
   Date: 31 January 2025.
3. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
   Date: 30 November 2024.
4. Submit any revisions of the audit strategy produced under measure (c)2.
   Date: Within 1 month of a revision.
5. Submit a report in the event that any completed measures of this Notice need to be altered in any way, for any reason.
   Date: Ongoing for the duration of this Notice.
6. Submit a satisfactory completion report, accompanied by a revised regulation 28(1) report with Board level Director sign-off.
   Date: 31 January 2026.

Further Details of this Notice:

4. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
5. Under regulation 28(6) the Inspectorate, on behalf of the Secretary of State, may by notice served on the Company, revoke or vary this Notice.
6. Failure by the Company to comply with this Notice may result in enforcement proceedings under section 18 of the Water Industry Act 1991 (as amended).

Signed

Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
15 August 2024
Reference: UUT-2024-00001