Southern Water Services Limited – Network Storage Asset Health Refurbishments

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

Reference: SRN-2026-00005

Version Number: v1

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:

All Southern assets listed in Appendix A, Appendix B, and the associated supply systems.

Details of this Notice:

The Drinking Water Inspectorate (‘the Inspectorate’) has various received a regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the company dated 15 October 2025, 30 January 2026 and 29 June 2026, which states that there is or has been a significant risk of supplying water from the sites listed in the Appendices (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:

Description of Risk	Hazard/ Hazardous Event/ Parameter	Hazard I D
Structural integrity of asset at risk	No Supply	136865
Insufficient water supply to downstream consumers	No Supply	136866
Microbiological contamination due to ingress	Total Coliforms	38147
Microbiological contamination due to ingress	E. coli	38148
Microbiological contamination due to ingress	Clostridium Perfringens	38145
Microbiological contamination due to ingress	Enterococci	38149

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:

Undertake scheduled Southern Water operator site inspections of treated water storage assets.
Date: Ongoing for the duration of this Notice.
Undertake grounds maintenance at the standard frequency.
Date: Ongoing for the duration of this Notice.
Internally inspect treated water storage assets according to Southern Waters current reservoir programme.
Date: Ongoing for the duration of this Notice.
Carryout maintenance tasks at the water storage assets in accordance with Southern Water standards.
Date: Ongoing for the duration of this Notice.
Sample treated water storage assets to check compliance at the frequency defined by the annual Southern Water Sampling Programme.
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:

Provide a risk-based programme of refurbishment works to be completed in AMP8 in accordance with Ofwat’s final asset health determination and update the list of treated water tanks listed in Appendix A to identify those assets where work is to be undertaken in AMP 8 and those to be carried forward to AMP9.
Date: 31 March 2027.
Where there is a change to the risk-based programme of refurbishment works, inform the Inspectorate of the change.
Date: Within one month of the requirement to change the programme being known.
Complete the refurbishments identified for AMP8 and return to service the treated water storage tanks listed for the AMP8 in Appendix A.
Date: 31 March 2030.
Complete a strategic review of network storage rationalisation for the supply areas listed in Appendix B detailing work to be carried out in AMP9.
Date: 31 March 2030.

(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).
Date: 31 December 2026
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 the Appendices, or not to so supply unless the specified conditions below are satisfied:

(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.
Provide an annual report on progress with b milestone actions.
Date: 30 April each year.
Provide a report detailing the programme of refurbishment works to be completed in AMP8 accompanied by an updated list of the treated water storage tanks identifying those where work is to be carried out in AMP8 and those being carried forward to AMP9.
Date: 30 April 2027.
Where there is a change to the programme of refurbishment works, provide a report to the Inspectorate detailing the change, the reason for it and if there is a delay in completion of works and interim risk mitigations.
Date: Within one month of the change being made to the programme.
Provide a report on the completion of the AMP8 refurbishment and return to service of the treated water storage assets listed in Appendix A.
Date: 30 April 2030.
Provide a report on the outcomes of the strategic review of network storage rationalization for the supply areas listed in Appendix B detailing proposed work to be carried out in AMP9.
Date: 30 April 2030.
Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
Date: 31 January 2027
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 2032.

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 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

Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
13 October 2026
Reference: SRN-2026-00005

Appendix A

Asset ref	Asset name	Supply system ref	Supply system name
RK007	Colewood Strood WSR – Number 2	Y016	Medway West
RK056	Darland Chatham WSR Number 4 – North Cell	Y015	Medway East
RK055	Darland Chatham WSR Number 4 – South Cell	Y015	Medway East
RS038	Ditching Road Brighton WSR	Y007	Brighton
RS109	Dyke Road Brighton WSR	Y007	Brighton
RK037	Fleete Manston WSR 2	Y010	Thanet
RH022	Horseshoe Hill WSR	Y012	Hampshire Rural
RS047	Houndean Lewes WSR	Y007	Brighton
RK062	Kingsborough Minster IOS WSR Number 1 – East cell	Y010	Thanet
RK061	Kingsborough Minster IOS WSR Number 1 – West cell	Y010	Thanet
RS093	Newgate Hastings WSR East (2)	Y003/ Y016	Hastings/Medway West
RS092	Newgate Hastings WSR West (1)	Y003/ Y016	Hastings/Medway West
RS056	Nunnery Brighton WSR	Y007	Brighton
RI022	Osbourne WSR – East Cell	Y004	Isle of Wight
RI033	Osborne WSR – West Cell	Y004	Isle of Wight
RS066	Race Hill Brighton WSR	Y007	Brighton
RK020	Singlewell WSR – Number 2	Y016	Medway West
RH046	South Hill Southampton WSR	Y014	Southampton West
RK022	Southdown Halfway Houses WSR 2	Y010/ Y015	Thanet/ Medway East
RS072	Southover WSR	Y007	Brighton
RS073	ST Annes Lewes WSR West	Y007	Brighton
RS125	Steyning Upper Beeding West WSR (Old)	Y008	Sussex North
RS126	Swan Falmer WSR – North Cell A	Y007	Brighton
RS127	Swan Falmer WSR – South Cell B	Y007	Brighton
RS075	Tenants Hill WSR	Y009	Worthing
RS145	Udimore WSR – Cell 2	Y007	Brighton
RS132	Upper Nash Nutbourne WSR 2 – North Cell	Y008	Sussex North
RS133	Upper Nash Nutbourne WSR 2 – South Cell	Y008	Sussex North
RI030	Ventnor Low Level WSR	Y004	Isle of Wight
RS078	Whitehawk Brighton WSR	Y007	Brighton
RS079	Windmill Lewes WSR	Y007	Brighton
RS147	Wiston WSR – North Cell	Y009	Worthing
RS148	Wiston WSR – South Cell	Y009	Worthing
RK068	Woolmans Wood Chatham WSR 2 – West Cell.	Y015/Y016	Medway East/ Medway West

Appendix B

Supply system ref	Supply system name
Hampshire North	Y001
Kingsclere	Y005
Hampshire Rural	Y012
Southampton East	Y013
Southampton West	Y014
Winchester	Y011
Isle of Wight	Y004
Medway East	Y015
Medway West	Y016
Thanet	Y010
Brighton	Y007
Hastings	Y003
Sussex North	Y008
Worthing	Y009

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