United Utilities Water Limited – Treated Water Storage Tanks

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

Reference: UUT3563

Version Number: 7

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:

  • United Utilities Water Ltd owned treated Water Storage Tanks, including service reservoirs, break pressure tanks, pump suction tanks and any other structures used to store treated drinking water, downstream of Water Treatment Works compliance sample points in the United Utilities Supply Region.

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a set of regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 01 October 2015, which states that there is or has been a significant risk of supplying water from Treated Water Storage Tanks (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:

Hazard/ Hazardous Event/ Parameter

E.coli

Coliforms (Total)

Cryptosporidium

Taste and odour

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.
  1. 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. Inspection and Cleaning programme for Treated water storage tanks using robust flood testing procedure.
    Date: Ongoing for the duration of this Notice
  2. Enhanced sampling at the storage tanks using flow cytometry.
    Date: Ongoing for the duration of this Notice
  3. Maintenance and review of target chlorine residual and set points at the storage tanks.
    Date: Ongoing for the duration of this Notice
  4. Monitor coliforms, colony counts and chlorine residuals as part of the routine sampling programme within the downstream distribution system. Where there is a risk of cryptosporidium from ingress, cryptosporidium monitoring should be carried out.
    Date: Ongoing for the duration of this Notice
  5. Management of flora and fauna at the storage tanks.
    Date: Ongoing for the duration of this Notice
  6. Site security, operational equipment checks and storage tank external inspection visits.
    Date: Ongoing for the duration of this Notice
  7. Review as part of the DWSP risk assessment the water turn-over for all treated water storage tanks.
    Date: Ongoing for the duration of this Notice.
  8. Manage Treated water storage tanks levels based on demand and alarm set points to ensure turn-over is optimised.
    Date: Ongoing for the duration of this Notice
  9. Maintenance, calibration and verification of treated water tank level control systems.
    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. Review, revise and/or make operational and maintain, the following additional short-term measures;
  • Review and update DWSP risk assessments for all Treated water storage tanks that cannot be removed from supply.
    Date: Complete
  • Confirm high level interventions required for all Treated water storage tanks that cannot be taken out of supply.
    Date: Complete
  • Develop revised risk assessment process for Treated water storage tanks to accurately identify and capture potential risks to water quality from the environment.
    Date: Complete
  • Develop a procedure for the acceptance of all completed remedial work, including acceptance criteria and sign-off process.
    Date:
    Complete
  1. Make operational and maintain the following additional medium-term measures;
  • Using a risk-based approach to target assets in order of risk to water quality, carry out revised Drinking Water Safety Plan risk assessment using new approach for all Treated water storage tanks in the North West region.
    Date: Complete
  • Update the Drinking Water Safety Plan risk assessment and submit to the Inspectorate.
    Date: Complete
  1. Make operational and maintain the long-term measures identified below;
  • Using a risk-based approach to target assets listed in appendix A in order of risk to water quality, complete Internal Inspection and clean of all treated water storage tank compartments that can be taken out of supply using the robust flood testing procedure to ensure maximum coverage. Complete remedial work required on any tank found to have ingress.
    Date: Complete
  1. Make operational and maintain the long-term measures identified below for assets that cannot currently be removed from supply;
  • Using a risk-based approach to target assets listed in appendix A in order of risk to water quality, deliver a programme of work to facilitate isolation of treated water storage tanks that cannot currently be taken out of supply.
    Date: Complete
  • Once enabling works have been completed to isolate treated water storage tanks, complete internal inspection and cleaning of all compartments, using the robust flood testing procedure to ensure maximum coverage of the tank roof and joints. Complete remedial work required on any tank found to have ingress.
    Date: Complete

(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;
  • Enhanced monitoring for E. coli, coliforms, colony counts.
  • Where a risk of Cryptosporidium exists, monitoring should be carried out.
  • Full investigation of all detections of E. coli, coliforms or Cryptosporidium, or of a step change in colony counts.
    Date: Complete
  1. 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 Treated Water Storage Tanks, 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 and against the following milestones:
    Date: by 31 January each year.
  • Confirmation of audit strategy.
    Date: Complete
  • Confirmation (b) 1 short term measures of the interventions to enable all storage tanks to be taken out of supply.
    Date: Complete
  • Confirmation of (b) 2 medium term measures following completion of DWSP and water turn-over calculations for all treated water storage tanks, and identification of assets where interventions are required.
    Date: Complete
  • Confirmation of (b) 3 long term measure to complete internal inspections and cleaning of all storage tanks listed in appendix A that can currently be taken out of supply using robust flooding method to ensure maximum coverage.
    Date: Complete
  • Confirmation of (b)4 long term measure to deliver programmes of works to take all storage tanks out of supply.
    Date: Complete
  • Confirmation of (b)4 long term measure to complete internal inspections and cleaning of all storage tanks where the removal from supply has been enabled, using robust flooding method to ensure maximum coverage.
    Date: Complete
  1. Review the risk assessment for all sites and systems where work is undertaken, as required by Regulation 27(4) and subsequently submit a revised Regulation 28 report (in accordance with Regulation 28(1)) from time to time); an
    Date: within 1 month of completion of the risk assessment.
  2. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 July 2024

Further Details of this Notice:

  1. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
  2. 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.
  3. 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
6 November 2023
Reference: UUT3563 v7

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