Thames Water Utilities Limited – Tanks Inspection and Cleaning

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

Reference: TMS-2022-00001

Version Number: 2

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:

• All the chlorine contact tanks, service reservoirs and treated water tanks (hereafter collectively referred to as ‘tanks’) used to supply water for regulation 4(1) purposes by the Company.

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 21 October 2021, which state that there is or has been a significant risk of supplying water from the Company’s 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:

Description of Risk	Hazard/ Hazardous Event/ Parameter
Potential risks from storage of water in tanks; including contamination from ingress or egress, and microbiological re-growth.	Coliform bacteria
	Escherichia coli (E. coli)
	Enterococci
	Colony Counts
	Chlorine (chlorine free and total)

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. Operate all tanks in accordance with current company policy, standards and procedures, that align to recognised standards of good practice.
   Date: Ongoing for the duration of this Notice
2. Maintain risk-based enhanced (in addition to routine regulatory sampling) sampling for any tanks listed in Annex 1. This must include, as a minimum, colony counts, E. coli and coliforms.
   Date: Ongoing for the duration of this Notice
3. Maintain proactive external site inspections, grounds maintenance, site security and asset maintenance. This must include periodic inspections of hatches, seals, redundant assets, sample taps, overflows, washouts and air valves.
   Date: Ongoing for the duration of this Notice
4. Maintain appropriate contingency plans (including liaison with relevant stakeholders as appropriate) to protect human health.
   Date: Ongoing for the duration of this Notice
5. Keep under review residual chlorine concentrations 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:

1. Develop a programme of works (that includes robust ingression testing (e.g. flood or inundation testing) and completion of any tank remedial work required) using a risk-based approach, to carry out physical internal inspections of all tanks listed in Table 1 of Annex 1.
   Date: Complete
2. Review Annex 1 on at least a biannual basis to ensure that all tanks that have not been cleaned and physically internally inspected in the last 10 years or more (or are scheduled to go beyond this), are identified within the Annex. Update the regulation 28(1) risk assessment report as appropriate.
   Date: At least biannually by 31 May and 30 November each year
3. Within 3 months of the identification of a new tank requiring addition to Annex 1 (following a review completed under measure (b)2), update the programme of works (that includes robust ingression testing and completion of any remedial work required) to include the physical internal inspections for the identified tank.
   Date: Within 3 months of the identification of a tank requiring addition to Annex 1 (ongoing for the duration of the Notice).
4. Commence the programme of internal inspections developed in (b)1 (including any updates completed under measure (b)3) to completion. Maintain appropriate documentation of any remedial work completed.
   Date: Commence by 01 January 2023 thereafter, ongoing until its completion.
5. Keep the programme of internal inspections (developed under measure (b)1) under continuous review, ensuring prioritisation of inspections based on risk.
   Date: Commence by 01 January 2023 thereafter, ongoing for the duration of the Notice
6. Develop a programme of works to complete the enabling works (and the testing thereof) required to allow the internal inspections of the assets listed in Annex 1, Table 2 to take place.
   Date: Complete
7. Commence the enabling and testing programme of works developed under measure (b)6.
   Date: Commence by 01 January 2023 thereafter, ongoing until its completion.
8. Conduct a critical review of the effectiveness of the Company’s scheduling and delivery of internal inspections of tanks. Identify measures (as required) to address the findings of the critical review.
   Date: Complete
9. Implement the measures identified under (b)8.
   Date: 31 October 2023
10. Develop a risk-based approach to determine the cleaning and physical internal inspection frequency of all the Company’s tanks, to include as a minimum:

• Time since last inspected;
• Date of construction/age;
• Materials of construction/tank design;
• Water quality history (to include as a minimum E. coli, coliforms, and colony counts);
• Turnover and tank hydraulics;
• Points of potential ingress (hatches, seals, redundant assets, overflows, washouts, and air valves (and associated alarms, where applicable));
• Sample tap condition, tapping points, sample lines and material; and
• Any other risks related to individual tanks.
  Date: Complete

11. Commence the risk-based approach to cleaning and physical internal inspections of all tanks within the company’s supply area (developed under measure (b)10), to become the ‘business as usual’ implemented approach for completion of internal tank inspections.
    Date: commence by 01 November 2022
12. Assess the suitability of the Company’s current tank contingency plans and arrangements, with a view to determine any improvements required. This assessment must include a review of emergency plans, where a tank cannot readily be removed from supply.
    Date: Complete
13. Implement any improvements identified as necessary under the suitability assessment completed under measure (b)12.
    Date: Complete
14. Upon the discovery of active ingress into any of the company’s tanks;

• Implement immediate short term mitigation measures to ensure human health is protected;
• Design a solution to stop the ingress; and
• Implement a solution to stop the ingress.
  Date: Ongoing for the duration of the Notice

(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).
   Date: Complete
2. 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 Company’s 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.
   Date: by 31 January each year.
2. Submit the programme of work for the physical internal inspection for tanks listed in Annex 1 as required under measure (b)1 and confirm commencement of the inspection programme (measure (b)4).
   Date: Complete
3. Submit a list of any newly identified tanks under measure (b)2.
   Date: biannually by 30 June and 31 December each year
4. Submit any updated programme of works for the physical internal inspection of any tanks identified under measure (b)2 (as required under measure (b)3).
   Date: biannually by 31 August and 28 February each year
5. Following the completion of a tank inspection and any required remedial work (as identified in the programme of works, including updates), submit a report summarising the inspection findings and works completed.
   Date: After one month of the completion of a tank inspection to coincide with a biannual submission date of either 30 June or 31 December each year
6. Submit the programme of enabling works (measure (b)6) and confirm commencement of the enabling programme (measure (b)7).
   Date: Complete
7. Outline the findings of the critical review and any resulting required actions (measure (b)8).
   Date: Complete
8. Confirm completion of measure (b)9.
   Date: 30 November 2023
9. Outline the risk-based approach developed under measure (b)10 and confirm commencement of the risk-based approach.
   Date: Complete
10. Outline the findings of the assessment completed under measure (b)12 and confirm any identified required improvements.
    Date: Complete
11. Confirm completion of measure (b)13.
    Date: Complete
12. Where ingress has been found and the company are unable to take the tank out of supply immediately or keep the tank out of supply until the ingress has been stopped, this must be notified as an event to the Inspectorate under paragraph 9(1) of the Water Industry (Suppliers’ Information) Direction 2023. The company’s written notification under paragraph 9(2)(b) of the Direction must outline:

• the immediate mitigation measure implemented to protect human health; and
• the Company’s action plan to mitigate the risks associated with ingress in the medium to long term.
  Date: in line with the requirements of the Water Industry (Suppliers’ Information) Direction 2023 (and any subsequent amendments thereof)

13. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete
14. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision
15. 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
16. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 2 months following the completion of the inspection programme for assets in Table 1 of Annex 1.

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
06 September 2023
Reference: TMS-2022-00001 V2