Thames Water Utilities Limited – Shalford and Hungerford Turbidity Risks

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

Reference: TMS-2026-00001

Version Number: 1

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:

• Assets listed within Annex 1.

Details of this Notice:

1. The Drinking Water Inspectorate (‘the Inspectorate’) has received various regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the company dated between 15 January 2026 and 10 March 2026, which states that there is or has been a significant risk of supplying water from water from sites listed in Annex 1 (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	Hazard I D
Failure to subject water to sufficient preliminary treatment to prepare it for disinfection (regulation 26(1)(b) and 26(6)(b)); Failure to verify the effectiveness of the disinfection process (regulation 26(2)(b)); and Turbidity.	A002A – Turbidity Indicator	Mutliple hazard lines listed in Annex 1 including:Shalford 1 Munstead:TMS-4-T04S.002-MDCT168-T04S.002-A002A

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. Operation of all processes within defined operating ranges with appropriate triggers, responses and contingency procedures with associated review programmes.
   Date: Ongoing for the duration of this Notice
2. Online turbidity monitoring of water prior to disinfection with appropriate alarms and failsafe shutdowns where applicable.
   Date: Ongoing for the duration of this Notice
3. Ensure the water treatment works’ control and shutdown system are operational and that monitors are calibrated at predefined frequencies.
   Date: Ongoing for the duration of this Notice
4. Continuous monitoring of raw and treated water with control systems, alarmed operating limits and automatic shutdown as appropriate.
   Date: Ongoing for the duration of this Notice
5. Ensure that turbidity monitoring equipment is maintained in-line with manufacturers’ instructions.
   Date: Ongoing for the duration of this Notice
6. Water quality response procedures for: investigation of contraventions including process optimisation and reporting; customer complaints procedures; event response procedures for event actions and notification criteria.
   Date: Ongoing for the duration of this Notice
7. Up-to-date Site Operating Manual (SOM), defining normal operating ranges, triggers, response and contingency procedures, with controlled update and review programmes.
   Date: Ongoing for the duration of this Notice
8. The Company’s internal waiver process is followed where deviation from the Asset Standard is required. This must not affect compliance with the Regulations.
   Date: Ongoing for the duration of this Notice
9. Up-to-date and subject to continuous review, site specific disinfection policy, which identifies clearly and unequivocally how disinfection is achieved at the works.
   Date: Ongoing for the duration of this Notice
10. Maintain contingency plans (including liaison with relevant stakeholders as appropriate) to protect human health.
    Date: Ongoing for the duration of this Notice
11. Take all reasonable operational steps (and continue to enhance the effectiveness of those steps) to ensure water that is not compliant with the requirements of regulations 4 and 26 is prevented from entering supply.
    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. Complete the construction/installation and commissioning of the chosen solution
   Date: By the dates listed in annex 1.

(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: 31 July 2026
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 sites listed in Annex 1, 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. Provide a report evidencing the construction/installation and commissioning of the chosen solution by the dates listed in annex 1. Where appropriate this should include:
   • An appropriate maintenance regime for any installed processes.
   • Full integration of the new (or modified) processes into the site control and monitoring systems.
   • Updating of the Site-Specific Disinfection Policy and any associated site-specific procedures.
   • Updating of the Site Operating Manual and removal of all out-of-date material from circulation; and
   • Provisions of adequate training for all relevant personnel on the operation, repair and maintenance of the installed (or modified) process and the revised procedures, policies and manual.
     Date: By the dates listed in annex 1
3. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
   Date: 31 August 2026
4. Submit any revisions of the audit strategy produced under measure (c)2.
   Date: Within 1 month of a revision
5. 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
6. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
   Date: 31 August 2028

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
11 May 2026
Reference: TMS-2026-00001

TMS-2026-00001: Annex 1, Table 1, Table of assets affected and dates of completion

Site	Supply System Reference	Hazard Parameter	Hazard ID Ref	Date by when all (b) measures are to be completed	Date completion report is due, following DoB period
T04S.002 Shalford 1 Munstead	YTMS1195YTMS1232YTMS2009	A002ATurbidity	TMS-4-T04S.002-MDCT168-T04S.002-A002A	31 July 2027	31 August 2028
T04S.003 Shalford 2 Mount	YTMS1195YTMS1232YTMS2009	A002ATurbidity	TMS-4-T04S.002-MDCT168-T04S.003-A002A
T04S.004 Shalford 3 Frith Hill	YTMS1195 YTMS1232YTMS2009	A002ATurbidity	TMS-4-T04S.002-MDCT168-T04S.004-A002A
T04S.005 Shalford 4 Pewley	YTMS1195YTMS1232YTMS2009	A002ATurbidity	TMS-4-T04S.002-MDCT168-T04S.005-A002A
T06U.603 Hungerford	YTMS1204	A002A Turbidity – indicator	TMS-4-T06U.603-MDCT168-T06U.603-A002A	31 July 2026	31 August 2027