South East Water Limited – Halling Water Treatment Works Disinfection Risk

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

Reference: SEW-2018-00011

Version Number: 3

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:

  • T324T08 Halling 6 Bore New Treated (Greensand)
  • Z322 Halling Water Supply Zone

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 01 September 2018, which states that there is or has been a significant risk of supplying water from Halling Water Treatment 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:
    • Failure to meet requirements of Regulation 26, inadequate disinfection, due to a failure to demonstrate that disinfection contact time is met under all conditions.
    • Residual Disinfectant- Free
    • Residual Disinfectant- Total
    • Microbiological
  3. 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.


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

  1. Optimisation of all existing treatment processes.
    Date: Ongoing for the duration of this Notice
  2. Operation of all processes within defined normal operating ranges with appropriate triggers, responses and contingency procedures.
    Date: Ongoing for the duration of this Notice
  3. Online turbidity and chlorine monitoring with appropriate alarms and failsafe shutdown.
    Date: Ongoing for the duration of this Notice
  4. Enhanced and large volume operational monitoring for microbiological parameters at Halling Water Treatment Works and at the downstream commercial property supplied.
    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. Install interim monitoring on a suitable downstream location after disinfection to provide information for the verification of disinfection.
    Date: Complete
  2. The Company shall undertake an investigation of the existing disinfection system and confirm a programme of work to provide adequate disinfection under all circumstances and flow rates and include the following:
  • The point in the treatment process whereby disinfection is achieved (the point of disinfection) must be clearly defined.
  • The final sample point must be located at the end of the treatment process and be representative of water leaving the treatment process.
  • The disinfection system must take into account flow dynamics through the treatment works and contact main, and this must be established using appropriate techniques.
  • The disinfection system must provide safeguards such as automatic shutdown or failsafe systems to prevent untreated or partially treated water entering into supply.
  • Installation of monitoring for turbidity and chlorination to provide continuous verification of disinfection.
  • Provide clearly defined critical control points, and real time evidence that the target chlorine contact time is achieved.
    Date: Complete
  1. Install (or modify the existing) and commission the chosen disinfection system as defined by (b)2.
    Date: Complete
  2. Review the site-specific Disinfection Policy with associated site-specific procedures and report revisions of the document to the Inspectorate.
    Date: Complete
  3. Update the Site Operating Manual and remove all out-of-date material from circulation.
    Date: Complete
  4. Provide adequate training to operators as part of the commissioning process and for any revision of the Site Operating Manual completed under (b)5.
    Date: Complete (30 September 2022)

(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: Complete
  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 Halling Water Treatment Works, or not to so 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:

  1. Provide a progress report annually.
    Date: by 31 January each year.
  2. Provide a report on completion of (b)1.
    Date: Complete
  3. Provide annually a summary of results from the interim monitoring from (b)i including any subsequent actions taken.
    Date: Complete
  4. Provide a design specification for the proposed disinfection scheme described in (b)2. with dates for commissioning and completion of work.
    Date: Complete
  5. Submit a report on completion of the commissioning or modification of the chosen disinfection system (measure (b)3.), with an updated site-specific Disinfection Policy required (measure (b)4.) and an updated site operating manual (measure (b)5.).
    Date: Complete
  6. Evidenced completion of the training required under measure (b)6.
    Date: Complete
  7. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete
  8. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision
  9. 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
  10. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 October 2023

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).


Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
01 November 2022
Reference: SEW-2018-00011 v3

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