Notice of Regulation: Thames Water – Service Reservoirs
THE WATER SUPPLY (WATER QUALITY) REGULATIONS 2016 (AS AMENDED)
NOTICE UNDER REGULATION 28(4)
Thames Water Utilities Limited: Service Reservoirs, Inadequate Turnover and Chlorine Residual Risk
DWI Reference: TMS-2021-00004
Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Thames Water Utilities Limited, with registered number 02366661(hereinafter called ‘the Company’).
Assets affected: Service reservoirs listed in Annex 1
- The Drinking Water Inspectorate (‘the Inspectorate’) has received multiple regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 11 August 2021, which state that there is or has been a significant risk of supplying water from the service reservoirs listed in Annex 1 (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
- 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 | Hazard ID | Description of Risks |
|---|---|---|
Chlorine | Multiple risk assessment reports (Annex 1). | Inadequate turnover leading to low free chlorine residuals and consequential risk of biological failures. |
- The Company are required to satisfy the following:
Requirements
(a) to maintain the following measures for the period specified in each case:
- Enhanced sampling (in addition to routine regulatory sampling) for coliform bacteria and E. coli, colony counts and chlorine (free and total) at a frequency of twice a week from each service reservoir cell listed in Annex 1.
Date: Ongoing for the duration of the Notice from 01 September 2021 - Regular (minimum monthly) site visits for all cells listed, to include site security, service reservoir external inspection and operational equipment checks.
Date: Ongoing for the duration of the Notice - Regular Thames Valley and London Water Quality turnover assessment meetings to review chlorine residuals and turnover for service reservoirs.
Date: Ongoing for the duration of the Notice
(b) to review, revise or make operational the following measures, by the dates specified in each case:
- Undertake a review of turnover and chlorine residual risks for the sites listed in Annex 1. To include:
Date: 30 September 2022- a) Review the pumping and control strategy of the supplying water treatment works and transmission system. Where applicable, review the blend between chloraminated and chlorinated water and the effect on chlorine residuals.
- b) Review the service reservoir turnover trends. Include a review of the operational arrangements for water entering and leaving each cell and turnover within each cell.
- c) Review the suitability of the inlet and outlet positioning. The implications on representativeness of sampling should also be considered as part of the review.
- Following the review in (b)1. identify any remedial work or additional control measures that are required to improve turnover and chlorine residuals, and develop a plan including timeframes to complete the work required. Where relevant and where turnover within a cell is found to be a potential issue, modelling shall be considered for inclusion within the action plan.
Date: 31 December 2022 - Implement the plan developed in (b)2 and complete any work identified.
Date: By dates specified in Annex 2, Column B.
All Company’s Service Reservoirs:
- Develop a suitable companywide procedure for monitoring chlorine residuals and turnover to ensure that any potential risk to wholesomeness is identified and actioned in a timely manner.
Date: 30 September 2022 - a) Conduct a gap analysis to identify any sites where chlorine and turnover may present a potential risk to wholesomeness using the new procedure developed in (b)4.
Date: 31 March 2023 - b) Implement appropriate actions, in accordance with the new procedure, to address the findings of the gap analysis completed under (b)5.a).
Date: TBC
- a) Conduct a gap analysis to identify any sites where chlorine and turnover may present a potential risk to wholesomeness using the new procedure developed in (b)4.
- Implement the procedure developed under measure (b)4., train relevant personnel on the procedure, and implement a ‘business as usual’ forward-reaching programme of review and training for the new procedure.
Date: 28 February 2023
(c) to audit whether the measures have been effective by the following means:
- Define an audit strategy to monitor the effectiveness of the above measures specified in section (a) and (b), including an audit into turnover and chlorine residuals 12 months following the implementation of mitigation measures.
Date: 30 November 2021 - 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 the sites listed in Annex 1 unless the conditions specified below are satisfied:
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:
- Provide a progress update annually by 31 January and against the following milestones:
Date: Annually by 31 January- a) Provide a summary of the review as stipulated in (b)1. and confirm any remedial work or additional control measures required to improve turnover and chlorine residuals, as specified in step (b)2., including the plan with proposed timeframes to complete any work required.
Date: 31 January 2023 - b) Confirm completion of the plan and any work required, as specified in (b)3.
Date: 1 month following the dates specified in Annex 2, column B. - c) Provide the procedure developed for monitoring chlorine residuals and turnover, as specified in (b)4.
Date: 31 October 2022 - d) Provide evidence that the procedure has been implemented and that relevant personnel have been trained on the new procedure, as specified in (b)6.
Date: 31 March 2023 - e) Confirm completion of gap analysis and any sites where chlorine and turnover may present a potential risk to wholesomeness, as specified in (b)5.a). Confirm the projected completion date for (b)5.b).
Date: 30 April 2023 - f) Confirm completion of measure (b)5.b)
Date: TBC
- a) Provide a summary of the review as stipulated in (b)1. and confirm any remedial work or additional control measures required to improve turnover and chlorine residuals, as specified in step (b)2., including the plan with proposed timeframes to complete any work required.
- Submit the strategy for auditing the effectiveness of the measures, as specified in (c)1.
Date: 31 December 2021 - Submit any revisions of the audit strategy produced under measure (c)2.
Date: Ongoing for the duration of this Notice - Submit a report in the event that any completed measure of this Notice needs to be altered in any way for any reason.
Date: Ongoing for the duration of this Notice - Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off for each individual service reservoir, following the completion of all section (b) measures, subsequent 12 months of successful auditing at each site and one month for report compilation.
Date: By the dates specified in Annex 2, Column C for each individual service reservoir.
- Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
- 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.
- 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
Nick Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
02 November 2021
Reference: TMS-2021-00004
Version Number: 2
Annex 1
Categorisation of sites included in this notice, reference numbers and relevant Hazard IDs.
Site name | Site reference | Hazard IDs |
|---|---|---|
Okus | RSR0256 | TMS-5-RSR0256-HEID065-RSR0256-H027 |
Burford A | RSR7088 | TMS-5-RSR7088-HEID065-RSR7088-H027 |
Burford B | RSR7087 | TMS-5-RSR7088-HEID065-RSR7087-H027 |
Wootton A | RSR7120 | TMS-5-RSR7120-HEID065-RSR7120-H027 |
Wootton B | RSR7121 | TMS-5-RSR7120-HEID065-RSR7121-H027 |
Wootton C | RSR7119 | TMS-5-RSR7120-HEID065-RSR7119-H027 |
Worsham A | RSR7145 | TMS-5-RSR7145-HEID065-RSR7145-H027 |
Worsham B | RSR7146 | TMS-5-RSR7145-HEID065-RSR7146-H027 |
Worsham C | RSR7128 | TMS-5-RSR7145-HEID065-RSR7128-H027 |
Worsham D | RSR7129 | TMS-5-RSR7145-HEID065-RSR7129-H027 |
Blacklains A | RSR7095 | TMS-5-RSR7095-HEID065-RSR7095-H027 |
Blacklains B | RSR7096 | TMS-5-RSR7095-HEID065-RSR7096-H027 |
Sewardstone Green A | RSR0306 | TMS-5-RSR0306-HEID065-RSR0306-H027 |
Sewardstone Green B | RSR0017 | TMS-5-RSR0306-HEID065-RSR0017-H027 |
Headington A | RSR6037 | TMS-5-RSR6037-HEID065-RSR6037-H027 |
Headington B | RSR6038 | TMS-5-RSR6037-HEID065-RSR6038-H027 |
Annex 2
Dates by site, for completion of all (b) measures and for the completion report submission.
Column A | Column B | Column C |
|---|---|---|
Service Reservoir | Date by when all (b) measures are to be completed by | Date by when the completion report is due, following 12 months of successful audit and 1 month for report compilation |
Okus Service Reservoir | TBC | TBC |
Burford SR: | TBC | TBC |
Wooton SR: | TBC | TBC |
Worsham SR: | TBC | TBC |
Blacklains A | TBC | TBC |
Sewardstone Green A | TBC | TBC |
Headington SR: | 31 March 2022 | 30 April 2023 |