Southern Water Services Limited – Borehole Asset Health Replacements

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

Reference: SRN-2026-00001

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 received various regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the company dated 21 June 2022, 15 October 2025 and 15 December 2025, 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	136136
Insufficient water supply to downstream consumers	No Supply	136137
Compromised disinfection process	Turbidity	70660
Microbiological contamination due to ingress	Total Coliforms	61769
Microbiological contamination due to ingress	E. coli	61770
Microbiological contamination due to ingress	Clostridium Perfringens	61767
Microbiological contamination due to ingress	Enterococci	61771

Table 2: 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 borehole headworks at the required frequency.
Date: Ongoing for the duration of this Notice.
Undertake grounds maintenance at the standard frequency.
Date: Ongoing for the duration of this Notice.
Carryout maintenance tasks at groundwater abstraction assets in accordance with Southern Water standards.
Date: Ongoing for the duration of this Notice.
Undertake raw water sampling at the frequency defined by the annual Southern Water Sampling Programme.
Date: Ongoing for the duration of this Notice.
Ensure the operating plan for the water supply works is followed where blending of individual boreholes is required to maintain compliance.
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:

Programme the works required for the drilling of replacement boreholes in accordance with the Ofwat final asset health determination and list those abstraction assets to be replaced in AMP8 and those to be carried forward to AMP9 in an update to Appendix A.
Date: 31 March 2027.
Complete the drilling and commissioning of replacement boreholes for the assets listed for completion in AMP8 in Appendix A.
Date: 31 March 2031.
Programme the decommissioning of assets in accordance with the Ofwat final asset health determination and list those assets for decommissioning in AMP8 and those carried forward to AMP9 in Appendix B.
Date: 31 March 2027.
Complete the decommissioning of assets listed for decommissioning in AMP8 in Appendix B.
Date: 31 March 2031.
Where there is a change to any of the programmes of works listed in measures b(1), or b(3), inform the Inspectorate, detailing the reason for the change.
Date: Within one month of the proposed change being known.

(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: by 30 April each year.
Provide a risk-based programme of works required for the drilling of replacement boreholes identifying those for completion in AMP8 and those to be carried forward to AMP9 in an updated Appendix A.
Date: 30 April 2027.
Provide a report on the completion of the drilling and commissioning of replacement boreholes for the assets listed for completion in AMP8 in in Appendix A.
Date: 30 April 2031.
Provide a risk-based programme of works for the decommissioning of assets identifying those for completion in AMP8 and those to be carried forward to AMP9 in an updated Appendix B.
Date: 30 April 2027.
Provide a report on the completion of decommissioning activities at the raw water assets listed for completion in AMP8 as defined in Appendix B.
Date: 30 April 2031.
Provide an updated programme where there is a change to any of the programmes of works listed in measures b(1), or b(3).
Date: Within one month of the change being made to the programme.
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
19 October 2026
Reference: SRN 2026-00001

Appendix A

Asset ref	Asset name	Supply system ref	Supply system name
AI016	Knighton Farm Borehole 1 UGS	Y004	Isle of Wight
AI017	Old Mill Knighton Borehole 2 UGS	Y004	Isle of Wight
AH052	Overton Borehole 2 UGS	Y001	Hampshire North
AS094	Rotherfield Midhurst Borehole 3 UGS	Y008	Sussex North
AS061	Surrenden Crescent Brighton BH UGS	Y007	Brighton

Appendix B

Asset ref	Asset name	Supply system ref	Supply system name
AKXX1	Capstone Greensand Borehole 2 UGS	Y015	Medway East
AI026	Carisbrooke Borehole 3 UGS	Y004	Isle of Wight
TBC	Harts Ash Knighton UGS	Y004	Isle of Wight
AS054	Lodsworth Borehole 3 UGS	Y008	Sussex North
TBC	Otterbourne Borehole F UGS	Y013	Southampton East
TBC	Rogate Borehole 1 UGS	Y008	Sussex North
TBC	Rogate Borehole 2 UGS	Y008	Sussex North
AS092	Rotherfield Midhurst Borehole 1 UGS	Y008	Sussex North
AS093	Rotherfield Midhurst Borehole 2 UGS	Y008	Sussex North

Print page