Dwr Cymru Cyfyngedig – Service Reservoirs and Treated Water Tanks

Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018

Reference: DWR-2021-00002

Version Number: 6

Water undertaker as appointed under section 6 of The Water Industry Act 1991 (as amended): Dwr Cymru Cyfyngedig, with registered number 02366777 (hereinafter called ‘the Company’).

Assets Affected:

The chlorine contact tanks, service reservoirs, and treated water storage tanks (hereafter collectively referred to as ‘tanks’) within the Company’s supply region.

Details of this Notice:

The Drinking Water Inspectorate (‘the Inspectorate’) has received multiple regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2018 (‘the Regulations’) from the Company dated between 01 January 2020 and 31 December 2021, which states that there is or has been a significant risk of supplying water from service reservoirs, contact tanks, and treated water storage tanks in the Company supply system, and associated assets as applicable – listed in Annex 1, 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 Welsh Ministers, under regulation 28(4) for the assets listed above, for risks associated with:

Description of Risk	Hazard/ Hazardous Event/ Parameter	Hazard I D Multiple hazard lines e.g:
To address the potential risks of ingress and microbial growth.	Total coliforms (confirmed)	D152784
To address the potential risks of ingress and microbial growth.	E. coli (confirmed)	D152785
To address the potential risks of ingress and microbial growth.	Enterococci	D152786
To address the potential risks of ingress and microbial growth.	Microbiological	D118723
To address the potential risks of ingress and microbial growth.	Chlorine	D118730

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.

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:

Operate all tanks in accordance with company policy, standards, and procedures, aligning with recognised standards of good practice.
Date: Ongoing for the duration of this notice
Maintain enhanced monitoring (in addition to statutory sampling) for, as a minimum, colony counts, E. coli, and total coliforms. This must include:

Enhanced sampling pre-inspection for tanks included in Annex 1 that are over the 10-year internal inspection frequency as specified in (b)1.a).
Enhanced sampling for 12 months post-inspection (on return to service) for tanks listed in Annex 1 where significant remedial work has been required based on measure (b)1.b) and where tanks have failed based on measure (b)1.c).
Date: Ongoing for the duration of this notice

Carry out annual Remotely Operated Vehicle (ROV) surveys for all tanks listed in Annex 1 that are over the 10-year internal inspection frequency.
Date: Ongoing for the duration of this notice
Carry out investigatory sampling in response to any microbiological exceedances, in line with company procedures at all of the company’s service reservoirs and treated water storage tanks.
Date: Ongoing for the duration of this notice
Maintain proactive, external site inspections, grounds maintenance, site security and asset maintenance programme at all of the company’s treated water tanks, including periodic inspections of hatches, seals, redundant assets, sample taps, overflows, washouts, and air valves. Ensure these checks are documented.
Date: Ongoing for the duration of this notice
Maintain records and evidence of the identification, decision making, and completion of remedial work on all the company’s treated water tanks, to ensure a robust audit trail.
Date: Ongoing for the duration of this notice
Maintain appropriate contingency plans for any tanks listed in Annex 1 (including liaison with relevant stakeholders as appropriate) to protect human health.
Date: Ongoing for the duration of this notice
Keep residual chlorine concentrations under continuous review for any tanks listed in Annex 1 to ensure appropriate set points and trigger values are in place to prevent a deterioration of drinking water quality.
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:

Review and update Annex 1 on at least a biannual (twice per year) basis and update the regulation 28(1) risk assessments as appropriate. Annex 1 updates to include:
a) Any tanks outside of the 10-year cleaning and internal inspection frequency (ongoing for the duration of this notice).
b) Any tanks where a structural issue has been identified on the tank that requires significant remedial work (ongoing for the duration of this notice).
c) Any tank where a breach of a bacteriological parameter as prescribed in Schedule 1 Table A (Part 2) of the Water Supply (Water Quality) Regulations 2018 (from 1 January 2021 and ongoing for the duration of this notice) in a sample taken for these purposes from the tank.
Date: Biannually by 31 May and 30 November each year
Develop a programme of work (including any enabling works required, flood testing, and completion of any remedial work required), using a risk-based approach to prioritisation, to carry out physical internal inspections and cleaning of all tanks listed in Annex 1. The company should ensure that no tanks within the company’s supply area fall outside of the 10-year internal inspection frequency by 31 March 2025.
Date: By 31 May 2022 and within 3 months of a tank being added to Annex 1
Implement the programme of physical internal inspections developed in (b)2. to completion. Maintain appropriate documentation of any remedial work completed.
Date: 31 March 2025
Develop and implement an independent procedure to identify all defects following physical internal inspections and to rectify any that impact water quality and evidence completion of repairs. The procedure should include a requirement to document the justification for any defects not rectified. The process should include sign-off of remedial work by a Senior Operational Manager when complete. Ensure all relevant personnel are trained on this procedure.
Date: Complete
Develop and implement a quality assurance procedure to ensure inspections (including external, internal, ROV, and sample tap inspections) are completed correctly and satisfactorily. To include:

Checks that current versions of forms are being used;
Training is delivered to relevant staff when new versions of documents are issued;
Checks that escalation procedures are followed correctly;
Escalation reporting is carried out when risks to water quality are identified or parts of the inspection are unable to be completed, for example if there are access issues.
Date: Complete

Conduct a gap analysis of the company’s procedure for verifying the effectiveness of repairs completed during internal inspections, including critical review of the company’s flood test procedure, benchmarking against industry good practice. Review and update the company’s procedure based on the findings of this analysis, to ensure that the revised flood test procedure is robust and representative. Ensure the procedural update is communicated to all relevant personnel and provide training on the updated procedure.
Date: Complete
For the tanks listed in Annex 1, carry out replacement of any sampling facilities that do not comply with the company standard.
Date: In line with schedule of work defined in (b)2. And by 31 March 2025.
Review and update as appropriate the contingency plans for removal from supply for all tanks listed in Annex 1. To include as a minimum, a review of:

Alternative supply arrangements;
Rezoning options;
Bottled water collection locations;
Sampling locations, frequency, and parameters;
Checks of critical valves.
Date: 30 November 2022 and within 3 months of a tank being added to Annex 1. To be updated within 3 months following completion of each internal inspection defined in (b)2.

Develop and implement a risk-based approach and schedule to determine the cleaning and physical internal inspection frequency for all tanks (with the exception of pressurised tanks that will be subject to inspection within a maximum frequency of 10 years) within the company’s supply area, within a maximum frequency of five years. To include, as a minimum:

Time since last inspection;
Date of construction and age;
Material of construction and tank design;
Presence of a waterproof roof membrane and date of installation;
Water quality history (to include as a minimum E. coli, total coliforms, and colony counts);
Turnover and tank hydraulics;
Chlorine residual trends and manual dosing interventions;
Findings of any recent ROV inspections and external inspections;
Points of potential ingress (hatches, seals, redundant assets, overflows, washouts, and air valves);
Sample tap condition, tapping points, sample lines and material;
Any other risks related to individual tanks.
Date: Complete

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

Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b). To include as a minimum:
a) The parameters, type (e.g. volume), frequency, and duration of the enhanced monitoring as specified in measure (a)2., for tanks listed in Annex 1 under each category defined in measure (b)1.
b) The frequency of proactive external inspections carried out in line with measure (a)5.
c) Define the threshold for ‘significant remedial work’, as specified in measure (b)1.b)
Date: Complete
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 tanks, or not to so supply unless the specified conditions 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 report annually.
Date: by 31 January each year.
Submit the programme of work for the physical internal inspection for tanks listed in Annex 1, demonstrating the risk-based approach to prioritisation, as specified in measure (b)2. For each tank provide justification of the decision of prioritisation.
Date: Complete
Submit a list of any newly identified tanks to be included in Annex 1 and an updated programme of works, as required under measures (b)1. and (b)2., respectively. For any tanks listed in Annex 1, completed in advance of 31 March 2025, submit evidence demonstrating satisfactory completion of the internal inspection, flood testing, any remedial work completed (evidence of sampling facility replacement (b)7. where appropriate), and enhanced monitoring with an accompanying regulation 28(1) report for the tank and an updated Annex 1 list for this notice.
Date: Biannually by 30 June and 31 December each year
Provide the procedure developed as specified in measure (b)4. and provide evidence that the procedure has been implemented and all relevant staff have been trained on this procedure.
Date: Complete
Provide the quality assurance procedure developed under measure (b)5., and provide evidence of implementation of this procedure, including training for all relevant staff.
Date: Complete
Provide a summary of the results the of the gap analysis, as specified in (b)6. Provide the updated flood test procedure as a result of the outcome of the gap analysis and provide evidence that all relevant staff have been trained on the updated procedure.
Date: Complete
Provide a summary of the review of contingency plans for all tanks listed in Annex 1, including evidence of where contingency plans have been updated as a result of the review.
Date: 31 December 2022 and then biannually by 30 June and 31 December each year.
Provide evidence of the implementation of the risk-based approach and schedule to determine the cleaning and physical internal inspection frequency for all tanks within the company’s supply area, as specified in (b)9.
Date: Complete
Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
Date: Complete
Submit any revisions of the audit strategy produced under measure (c)2.
Date: Within 1 month of a revision
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.
Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
Date: 30 April 2026

Further Details of this Notice:

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 Welsh Ministers, 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

Nicholas Adjei
Deputy Chief Inspector, on behalf of the Welsh Ministers
05 August 2024
Reference: DWR-2021-00002 v6

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