South East Water Limited – West Ham Water Treatment Works – Nitrate

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

Reference: SEW-2023-00013

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:

Asset Name


West Ham Treatment Works Supply System 


Table 1: List of assets affected and associated reference numbers

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 30 November 2023, which states that there is or has been a significant risk of supplying water from West Ham WTW (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:

Description of Risk

Hazard/ Hazardous Event/ Parameter

Hazard I D

Potential risks to drinking water quality and non-compliance with the Water Supply (Water Quality) Regulations. 












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.
  1. 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. Continued implementation of raw water management strategy to ensure treatment processes are not compromised and forced to operate outside operational limits
    Date: Ongoing for the duration of this Notice
  2. The Company will evaluate and determine the most suitable method to blend the source waters to reduce the nitrate concentration in the final water accordingly to ensure compliance with the regulations. 
    Date: Ongoing for the duration of this Notice
  3. Weekly water sampling of raw and final waters for nitrate. 
    Date: Ongoing for the duration of this Notice
  4. Continuation of catchment management working with stakeholders to reduce input from sources, understand activities contributing to nitrate in catchment and put in place and maintain appropriate mitigations for areas at high risk. 
    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 online nitrate monitors on all raw water sources.
    Date: 31 October 2025
  2. Complete investigation into the operation and blending of the West Ham and West Ham Park boreholes. 
    Date: 31 October 2025
  3. Plan and design the option to mitigate risk of nitrate at West Ham Treatment Works. 
    Date: 31 October 2025
  4. Install and commission treatment at West Ham Treatment Works to mitigate the risk of nitrate. Commissioning must include the following to allow for the changes made: 
  5. An appropriate maintenance regime for nitrate treatment; 
  6. Full integration of the new processes into the site control and monitoring systems;
  7. Updating of the Site Specific Disinfection Policy and any associated site-specific procedures;
  8. Updating of Site Operating Manual and removal of all out of date material from circulation; and 
  9. Provide adequate training to operators as part of the commissioning process and for any revision of the Site Operating Manual completed under (b)2. 
    Date: 31 March 2027

(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: 31 March 2024
  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 Barcombe Storage, 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. Confirm installation of nitrate monitors on all raw water sources.
    Date: 30 November 2025
  3. Submit report summarising the findings of the investigation into the operation and blending of the West Ham and West Ham Park boreholes. 
    Date: 30 November 2025
  4. Submit a report on completion of the commissioning or modification of the chosen treatment option (measure (b)3), with an updated site-specific Disinfection Policy, an updated site operating manual and evidence of completion of training required. 
    Date: 30 April 2027
  5. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: 30 April 2024
  6. Submit any revisions of the audit strategy produced under measure (c)2.
    Date: Within 1 month of a revision
  7. 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
  8. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 30 April 2028

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
5 January 2024
Reference: SEW-2023-00013

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