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Southern Water Services Limited – Weirwood Multi Phase

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

Reference: SRN-2024-00016

Version Number: 3

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Southern Water Services Limited, with registered number 02366670 (hereinafter called ‘the Company’).

Assets Affected:

Table 1: List of assets affected and associated reference numbers

Asset Name

Reference

Weirwood Forest Row Works

TS009

Weirwood Forest Row Supply System

Y040

Details of this Notice:

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a regulation 28(1) report of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 19 November 2018, which states that there is or has been a significant risk of supplying water from Weirwood Forest Row Water Supply Works (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:

Table 2: Table of the hazards, hazardous events, and/or parameters covered by this Notice, including the Hazard ID numbers and the description of risks.

Description of Risk

Hazard/ Hazardous Event/ Parameter

Hazard I D

Catchment risks and failure or treatment process

Clostridium perfingens

47073

Catchment risks and failure or treatment process

E. coli

47076

Catchment risks and failure or treatment process

Enterococci

47077

Catchment risks and failure or treatment process

Total Coliforms

47075

Catchment risks and failure or treatment process

Parasites

(Cryptosporidium)

47072

Insufficient water supply to downstream consumers

No Supply

47131, 47132, 47133

  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. Continue progressing the Sussex North schemes, in order to support the Hardham works supplies to customers in the Sussex North Resource Zone while the new treatment stream at Weirwood works is being built.
    Date: Ongoing for the duration of this Notice
  2. Ongoing monitoring of regulatory and operational sample results and online data, once available.
    Date: Ongoing for the duration of this Notice
  3. Enhanced sampling for colony counts (at 22oC), TOC, coliforms and E. coli in the treated water supplied.
    Date: Ongoing for the duration of this Notice
  4. To monitor treated water supplied using flow cytometry.
    Date: Ongoing for the duration of this Notice
  5. Carry out Remote Operated Vehicle (ROV) surveys at frequency set out in audit strategy.
    Date: Ongoing for the duration of this Notice
  6. Enhance the frequency of interstage sampling to enable more granular monitoring and optimisation of the treatment process.
    Date: Ongoing for the duration of this Notice
  7. Enhanced monitoring (as a minimum 3 times per week) for Cryptosporidium in the raw and treated water.Date: Ongoing for the duration of this Notice
  1. Establish and maintain in place until improvement works are completed such enhanced operational measures as necessary to ensure that consumers are protected, and water supplied from the site is adequately treated and wholesome.
    Date: Ongoing for the duration of this Notice
  2. Liaise with UK Health Security Agency and local authorities in the event of any breach of a health-based standard.
    Date: Ongoing for the duration of this Notice
  3. Maintain and operate works treatment in accordance with works site specific maintenance schedule and Routine Site Task Lists.
    Date: Ongoing for the duration of this Notice
  4. Produce daily working weekday trends review in accordance with WSM 202.06 to flag all risks and potential opportunities for process optimisation.
    Date: Ongoing for the duration of this Notice
  5. Validate dosing flow monitoring at a frequency commensurate with treatment changes and as a minimum in line with manufacturer’s instructions.
    Date: Ongoing for the duration of this Notice
  6. Continuous on-line monitoring of chlorine concentration and turbidity with appropriate alarm levels and automatic shutdown pre and post disinfection.
    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. Confirm the programme of works for the new Weirwood works, including the programme for completion of:
    a) Construction.
    b) Commissioning.
    c) Asset Integration.
    d) Training of operational staff.
    e) Supply of water from Weirwood works into the downstream supply network.
    Date: Complete.
  2. Confirm the completion of the following at Weirwood works:
    a) Construction of 20ML/day plant.
    b) Commissioning of 20 ML/day plant.
    c) Asset Integration of 20Mld plant.
    d) Training of operational staff on the new operation and maintenance of the new water treatment processes.
    e) Supply of water from Weirwood works into the downstream supply network.
    Date: 31 December 2030

(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: 30 April 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 Weirwood Forest works, or not to so supply unless the specified conditions below are satisfied:

  1. To keep sampling and any inspections under constant review and cease supply if any Water Quality deterioration observed. In such an event, the Inspectorate, the local council and UKHSA is to be informed immediately.
    Date: For 6 months post Phase 1 returning to supply

(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. At regular intervals, provide the Inspectorate with reports on progress made.
    Date: Bi-annually, on last day of May and November for the duration of the notice.
  3. Provide a report confirming the programme of works for Phase 1, 2, 3 of the new Weirwood works, including the programme for completion of:
    a) Construction.
    b) Commissioning.
    c) Asset Integration.
    d) Training of operational staff.
    e) Supply of water from Weirwood works into the downstream supply network.
    Date: Complete.
  4. Submit application as per Regulation 15 (1) (a) before bringing supply back to work.
    Date: At least 1 month prior to returning to supply
  5. Provide a report confirming the completion of the following at Weirwood works:
    a) Construction of 20ML/day plant.
    b) Commissioning of 20 ML/day plant.
    c) Asset Integration of 20Mld plant.
    d) Training of operational staff on the new operation and maintenance of the new water treatment processes.
    e) Supply of water from Weirwood works into the downstream supply network.
    Date: 31 January 2031.
  6. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete.
  7. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision.
  8. 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.
  9. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 January 2032.

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).
  4. Contravention of a regulation 28(4)(d) requirement is an offence under regulation 33(1). If guilty of such an offence, the Company is liable on summary conviction, or on conviction on indictment, to a fine. Under regulation 33(2) it is a defence for the Company to show that it took all reasonable steps and exercised all due diligence to avoid the commission of the offence.

Signed

Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
28 August 2026
Reference: SRN-2024-00016 v3

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