Current improvement programmes

Notice of Regulation: Penton Lower Service Reservoir




Assets affected:

  • Prenton Lower Service Reservoir.
  • Wirral UUL1523.
  • R437 Prenton Upper SR.

Improvement Programme Database Reference number – UUT3480


  1. has received a report from United Utilities (the “Company”) dated 30 June 2015 (the “Report”) which states that there is or has been a significant risk of supplying water from Prenton Lower Service Reservoir (SR) that would constitute a potential danger to human health.
  2. Gives Notice that the Company is required, in order to mitigate the risk, in accordance with Regulation 28(4):

For risks associated with:

Ingress of service reservoir by contaminates including;

  • Coliforms and Escherichia coli
  • Other pathogens

(a) to maintain the existing operational measures set out in the Report and as specified below:

Date: until revocation of this notice

  1. Regulatory sampling programme at SR.
  2. Enhanced sampling at the SR for bacteriological parameters and chlorine residuals.
  3. Maintenance and review of target chlorine residual and setpoints at the SR.
  4. Monitor coliforms, colony counts and chlorine residuals as part of the routine sampling programme within the downstream distribution system.
  5. Management of flora and fauna at the SR.
  6. Management of the drainage at the SR.
  7. Weekly site security, operational equipment checks and SR external inspection visits.

(b) to review, revise and/or make operational such measures as are specified below, by the date specified below:

Short Term Measures

  1. In respect of bacteriological issues review frequency of enhanced
  2. sampling, site inspections and target chlorine and set points and take necessary measures to protect public health.
    Date: for duration of this Notice

Medium Term Measures

  1. Review, revise and/or make operational and maintain, the following additional medium-term measures appropriate to mitigate the risk:
    • Initiate capital programme to identify a solution to enable the isolation Prenton Lower SR. The final solution should be permanent in nature to allow future isolation for routine inspection and maintenance of this asset
      Date: by 30 June 2015.COMPLETE
    • Completion of the concept phase and issue of tender documents
      Date: by 31 October 2016. COMPLETE
    • Confirmation of the preferred permanent solution to isolate the SR, design and procurement
      Date: 31 January 2017. COMPLETE

Long term Measures

  1. Make operational, and maintain the long-term measures identified in below;
    • Completion of all capital works to enable isolation of the service reservoir
      Date: by 30 April 2023
    • Completed Isolation and abandonment of R437 Prenton Upper SR
      Date: by 31 May 2023
    • Internal Inspection of the service reservoir, identification of repairs in the reservoir structure or roof, clean and complete any identified repairs to the service reservoir structure and return to service
      Date: by 31 December 2023

(c) to audit whether the measures have been effective by such means as specified below:

  1. Define a strategy for auditing the effectiveness of the above measures
    Date: by 30 September 2015 COMPLETE
  2. Implement the audit strategy outlined in (c)2
    Date: until revocation of this notice.

(d) not to supply water for regulation 4(1) purposes from Prenton Lower and Prenton Upper Service reservoirs, or not to so supply unless the specified conditions below are satisfied:

  1. Not Applicable

(e) to provide the following information in such time and manner as specified below to enable monitoring of progress:

  1. Provide a progress report annually on 31 January and against the following milestones:
    • Confirmation of audit strategy
      Date: by 30 September 2015
    • Confirmation of the solution to enable isolation of the SR
      Date: by 31 January 2017 COMPLETE
    • Notify the DWI of any bacteriological infringement.
      Date: Immediately
    • Confirm completion of the ability for isolation of Prenton Lower Service Reservoir and abandonment of Prenton Upper Service Reservoir
      Date: by 31 May 2023
    • Confirmation of completion of the long term measures including inspection of the service reservoir and completion of all repairs to the service reservoir
      Date: by 31 January 2024
  2. Review the risk assessment for Prenton Lower Service Reservoir as required by Regulation 27(4) and subsequently submit a revised Regulation 28 report
    Date: (in accordance with Regulation 28(1)) from time to time); and two months after return to service
  3. Submit a satisfactory completion report
    Date: by 31 January 2025

Please be aware that breach by the Company of this Notice may result in an enforcement notice, breach of which may itself attract a penalty.

This Notice may be amended or revoked by notice from the Secretary of State at any time.

Signed by authority of the Secretary of State,
Nicholas Adjei
Deputy Chief Inspector
Date: 27 January 2022
DWI Reference: UUT3480
Version 5