Notice of regulation: South East Water Limited – 10+ Years Reservoir Inspection Programme

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

Reference: SEW-2021-00007

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:

  • All service reservoirs, treatment works’ disinfection/ treated water tanks and break pressure tanks within the company’s operating area.

Details of this Notice

  1. The Drinking Water Inspectorate (‘the Inspectorate’) has received a set of regulation 28(1) reports of the Water Supply (Water Quality) Regulations 2016 (as amended) (‘the Regulations’) from the Company dated 21 October 2021, which state that there is or has been a significant risk of supplying water from South East water tanks and service reservoir assets (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:

Hazard, Hazardous Event, or Parameter

Description of Risks

Total coliforms (confirmed), E. coli (confirmed), Clostridium perfringens (confirmed), Enterococci (confirmed), and colony counts at 22oC

To address the risk of ingress contamination and microbial growth.

  1. The Company are required to satisfy the following requirements.

The date given (the ‘date’) is that until/ by which requirements must be maintained/ satisfied, as appropriate.


(a) To maintain the following measures for the period specified in each case:

  1. Operate all service reservoirs and tanks in accordance with current company policy, standards and procedures aligning recognised standards of good practice.
    Date: ongoing for the duration of this notice.
  2. Enhanced microbiological monitoring where service reservoir has not been inspected in accordance with the company’s policy. Including; where new risks to water quality from the asset are identified.
    Date: ongoing for the duration of this notice.
  3. Complete frequent service reservoir maintenance check visits and escalate issues that present a water quality risk in accordance with company policy and procedures.
    Date: ongoing for the duration of this notice.
  4. Proactive grounds maintenance on all service reservoir sites and at outflow discharge points.
    Date: ongoing for the duration of this notice.
  5. Maintain records of remedial work completed on all cells. 
    Date: Ongoing for the duration of this notice. 
  6. Maintain contingency plans to protect human health in the event of a risk associated with drinking water quality, which should include liaison with local authorities and Public Health England. 
    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 which treated water storage tanks have not been physically drained and inspected within 10 years and record in Annex 1 and the Company’s DWSP.
    Date: Complete.
  2. Review Annex 1 on at least an annual basis to ensure that any tanks outside of the 10-year cleaning and inspection frequency are included and update the risk assessments for any site included within this list.
    Date: Annually by 31 May each year for the duration of the Notice and within 1 month of any asset included in or removed from the list.
  3. Using a risk-based approach:
    1. Conduct a review of how all treated water storage tanks/cells are removed from supply. 
      Date: 31 March 2022 
    2. Develop a plan and schedule of works (with timescales) to complete the physical manned internal inspections and any remedial works identified for all tanks listed in Annex 1. 
      Date: 30 June 2022 
    3. Implement this plan to completion for all tanks to ensure all tanks have been inspected within 10 years. 
      Date: 31 March 2025
  4. Review all treated water (and chlorine contact) tank schematics and ensure drawings are up to date and include locations of regulatory sample taps, any online water quality monitors, tapping points, the outflow discharge points and all relevant valves (including air valves). 
    Date: 31 March 2025 
  5. Define, produce and implement a refined risk-based programme of physical manned internal inspections and flood testing to ensure all treated water storage structures are inspected and flood tested at a maximum frequency of 10 years. Keep this programme under continuous review taking into account network and water resources constraints. 
    Date: 31 March 2025 
  6. Develop and implement a risk-based program of inspections for all treated water tank associated overflows, washouts, air valves and flap valves. 
    Date: 31 March 2023 

(c) To audit whether the measures have been effective by the following means:

  1. Define an audit strategy to monitor the effectiveness of the above measures specified in sections (a) and (b).
    Date: 30 April 2022.
  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 South East Water tanks and service reservoirs, or not to 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:

Provide a progress report annually by 31 January and against the following milestones:

  1. One month after completion of each measure in section (b). 
    Date: Within 1 Month after each measure in Section (b) 
  2. Submit the strategy for auditing the effectiveness of the measures, as specified in (c)1. 
    Date: 31 May 2022 
  3. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within one month of a revision.
  4. Submit a report in the event that any completed measure of this notice needs to be altered in any way for any reason.
    Date: ongoing for the duration of this notice.
  5. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 30 April 2025.

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).


Nick Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs.
15 February 2022
Reference: SEW-2021-00007 (V1)

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