South East Water Limited – Pembury Water Treatment Works Raw Water Treatment
Enforcement Order – Section 18 of the Water Industry Act 1991
Reference: SEW-2026-00004
Version Number: 1
Water undertaker as appointed under section 6 of the Water Industry Act 1991 (‘the Act’): South East Water Limited, with registered number 02679874 (hereinafter called ‘the company’).
Details of this Order:
- The company has failed to comply with its duties under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (‘the Regulations’). Specifically, the notice with reference SEW-2024-00006, served under regulation 28(2) of the regulations. The notice itself was required to mitigate the risk of supplying water that could constitute a danger to human health or which could be unwholesome, and thereby also needed for compliance with the company’s duty under section 68(1)(a) of the Act, with reference to regulation 4 of the Regulations.
- As part of its investigation into the Tunbridge Wells loss of supplies event (reference 2025/10706) the Inspectorate identified additional improvements required at Pembury water treatment works in order to mitigate the risk of the company failing to comply with its duty under section 68(1)(a) of the Act, with reference to regulation 4 of the Regulations.
- The company was notified on 7 May 2026 of the Inspectorate’s intention to make an enforcement order under section 18 of the Act in respect of the contraventions of the Regulations and the potential to contravene s. 68 of the Act.
- The Inspectorate has considered any representations or objections to the proposed order, which were duly made and not withdrawn.
- The Chief Inspector of Drinking Water makes this enforcement order under section 18 of the Act for the purposes of securing compliance with the Regulations and section.68 of the Act.
- The effect of this order is to place the company under a statutory obligation, which requires compliance with the steps and reporting outlined in the attached Schedule of Works. Failure to carry out the steps and reporting set out in the Schedule of Works will be considered a contravention of the requirements of the order.
- The obligation to comply with an enforcement order is a duty owed to any person who may be affected by a contravention of the order (section 22(1) of the Act). Please note that any breach of this duty may render the company actionable for any loss or damage caused by non-compliance by a person affected, subject to the statutory defence under section 22(3) of the Act. Failure to comply may also result in civil proceedings being brought against the company by the Chief Inspector in respect of any contravention or apprehended contravention for an injunction or for any other appropriate relief (section 22(4) of the Act).
Requirements:
- The company is hereby required to complete the steps and reporting outlined in the attached Schedule of Works with effect from the day after this order is made.
Signed
Marcus Rink
Chief Inspector of Drinking Water on behalf of the Secretary of State for Environment, Food and Rural Affairs
19 June 2026
Reference: SEW-2026-00004
Schedule of Works
South East Water Limited – Pembury Water Treatment Works
Date: 19 June 2026
Reference: SEW-2026-00004
Version Number: 1
Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): South East Water Limited, with registered number 02679874 (hereinafter called ‘the company’).
Assets Affected:
- T013 – Pembury Water Treatment Works
Steps to be taken:
The company is required to implement the following steps by the date given in each case.
Maintenance of existing measures;
- Optimisation of all existing treatment processes. Date: Ongoing for the duration of this Order
- Operation of all processes within defined normal operating ranges with appropriate triggers, responses and contingency procedures.
Date: Ongoing for the duration of this Order - Maintain annual visual checks of the aeration stage at Pembury Works.
Date: Ongoing for the duration of this Order - Complete monthly jar testing of raw and interstage treated water to verify current treatment processes are optimised.
Date: Ongoing for the duration of this Order - Undertake enhanced monitoring of the ongoing pesticide performance to understand the loading entering the raw water reservoir.
Date: Ongoing for the duration of this Order
Review, revise or make operational the following measures;
- Complete the remedial works highlighted in the sludge lagoons’ condition assessment.
Date: 31 December 2026 - Complete the installation and commissioning of a new contact tank. Date: 30 September 2028
- Complete the upgrading works of the boosters and the replacement of the MCC at Lilley Farm. Date: 30 September 2027
- Complete the maintenance work on the springs network. Date: 30 September 2028
- Complete the upgrading of the GAC treatment. Date: 30 September 2028
- Complete the enlargement to the capacity of the settlement tank. Date: 30 September 2028
- Complete the installation and commissioning of the new borehole at Matfield.
Date: 30 September 2028 - Complete a DAFF condition survey and replacement of flocculator motors.
Date: 30 September 2027 - Complete hydraulic improvements for Hartlake.
Date: 30 September 2028 - Increase the size of the current dirty wash water tank, install poly electrolyte dosing to thicken the backwash and sludge return flows. Upgrade the PLC/MCC of the sludge works, reprogramming the PLC for supernatant discharge and sludge density monitor control. Replace all valves with actuators.
Date: 28 February 2030 - Conduct a hazard review (“HazRev”) of Pembury water treatment works to identify single points of failure or other operational weaknesses within the treatment process.
Date: 31 October 2026 - Complete the planning, design, procurement, installation and commissioning of the required mitigations identified under step 16.
Date: 31 March 2030 - Complete the planning and design of;
- Automated flow-paced coagulant dosing with real-time monitoring.
- Real-time monitoring of pH, temperature, electrical conductivity (EC), turbidity, aluminium and other relevant parameters determined by the company, at critical stages within the treatment process. This should as a minimum include:
- Raw – EC, pH, temperature, turbidity
- Post DAFF – pH, turbidity, aluminium
- Post GAC – pH, turbidity, aluminium
- Redundancy for critical dosing.
Date: 31 March 2027
- Complete the procurement, installation and commissioning of the upgrades planned and designed under step 18 above. Date: 30 June 2027
- Define and implement an audit strategy to monitor the effectiveness of the company’s delivery of the steps within this order.
Date: 31 August 2026
Reporting
Provide the Inspectorate with the following reports as specified.
- Report: Twice per year progress reports
Detail: Provide reports on the progress made with implementing the steps to be taken. Reports should include a statement of implications of any delays to the steps to be taken and details of activities planned to bring the programme back on target.
Date: Twice per year, by 31 January and 31 July for the duration of the order - Report: Sludge lagoons – condition assessment actions
Detail: Submit a report confirming the completion of the remedial works highlighted in the sludge lagoons’ condition assessment, as specified in step 6.
Date: 31 January 2027 - Report: New contact tank
Detail: Submit a report confirming the completion and commissioning of the new contact tank, as specified in step 7.
Date: 31 October 2028 - Report: Lilley Farm boosters and MCC
Detail: Submit a report confirming the completion of the upgrading works of the boosters and the replacement and commissioning of the MCC at Lilley Farm, as specified in step 8.
Date: 31 October 2027 - Report: Springs network maintenance
Detail: Submit a report confirming the completion of the maintenance work on the springs network, as specified in step 9.
Date: 31 October 2028 - Report: GAC completion
Detail: Submit a report confirming the completion of the upgrading of the GAC treatment, as specified in step 10.
Date: 31 October 2028 - Report: Settlement tank completion
Detail: Submit a report confirming the completion of the enlargement to the capacity of the settlement tank, as specified in step 11.
Date: 31 October 2028 - Report: Matfield borehole
Detail: Submit a report confirming the completion of the installation and commissioning of the new borehole at Matfield, as specified in step 12.
Date: 31 October 2028 - Report: DAFF survey
Detail: Submit a report confirming the completion of the DAFF condition survey and replacement of flocculator motors, as specified in step 13.
Date: 31 October 2027 - Report: Hartlake hydraulic improvement
Detail: Submit a report confirming the completion of the hydraulic improvements for Hartlake, as specified in step 14.
Date: 31 October 2028 - Report: Wash water and sludge plant upgrades
Detail: Submit a report confirming the completion of the washwater and sludge plant upgrades, as specified in step 15.
Date: 31 March 2030 - Report: HazRev Report
Detail: Submit a report providing details of the hazard review carried out and required mitigations identified, as specified in step 16.
Date: 30 November 2027 - Report: HazRev Actions
Detail: Submit a report evidencing the completion of HazRev identified actions, as specified in step 17.
Date: 30 April 2030 - Report: Dosing upgrade designs
Detail: Submit a report providing details of all dosing system upgrades, as specified in step 18.
Date: 30 April 2027 - Report: Dosing upgrades
Detail: Submit a report evidencing the completion of actions associated with the installation and commissioning of flow-paced coagulant dosing, real-time monitoring at critical stages within the treatment process and the redundancy of for critical dosing, as specified in step 19.
Date: 31 July 2027 - Report: Delay or change report
Detail: If the company has any reason to believe it may not be able to meet any of the dates set out in this Schedule of Works, it must notify the Inspectorate as soon as reasonably practicable after being made aware and in any case, within one month.
Date: as soon as reasonably practicable after being made aware and in any case, within one month; ongoing for the duration of the order - Submit a report in the event that any completed step of this Order needs to be altered in any way, for any reason.
Date: As soon as reasonably practicable after being made aware and in any case, within one month; ongoing for the duration of the order - Submit the audit strategy for auditing the effectiveness of the measures and steps in this enforcement order, as specified in step 20.
Date: 30 September 2026 - Submit any revisions of the audit strategy.
Date: Within 1 month of a revision - Report: Completion report
Detail: Submit a satisfactory completion report accompanied by a Board level Director sign-off for the corresponding risk assessment.
Date: 31 May 2031