South East Water Limited – Cookham Treatment Work, Nitrate Risk

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

Reference: SEW-2024-00004

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:

Asset Name	Reference
Cookham Treatment Works Supply System	Y210

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 1 March 2024, which states that there is or has been a significant risk of supplying water from Cookham 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:

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.	Nitrate	T210-TREATMENT-A012 R202-STORAGE-A012 R223-STORAGE-A012 R224-STORAGE-A012 R247-STORAGE-A012 R248-STORAGE-A012 R249-STORAGE-A012 Z253-DISTRIBUTION-A012 Z261-DISTRIBUTION-A012

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.

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.

Requirements:

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

1. The Company will confirm that arrangements for blending are consistent with current industry best practice and all Drinking Water Inspectorate guidance and requirements of the Regulations.
   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. The Company will complete weekly water sampling of raw and final waters for nitrate.
   Date: Ongoing for the duration of this Notice
4. The Company will continue 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. Complete the installation and commissioning of online nitrate monitors on all raw water sources.
   Date: 31 October 2025
2. Complete the investigation into the operation and blending of the Cookham boreholes.
   Date: 31 October 2025
3. Plan and design the option to mitigate risk of nitrate at Cookham works as specified in the findings of measure (b)2.
   Date: 31 December 2025
4. Complete the installation and commissioning of the new treatment process at Cookham works to mitigate the risk of nitrate as specified in the findings of measure (b)3. 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.

Date: 31 May 2029

(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 October 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 Cookham 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. Submit a report confirming the completion of the installation and commissioning of the online nitrate monitors on all raw water sources as specified in measure (b)1.
   Date: 30 November 2025
3. Submit a report summarising the findings of the investigation into the operation and blending of the Cookham boreholes as specified in measure (b)2.
   Date: 30 November 2025
4. Submit a report outlining the chosen solution designed under measure (b)3. 
   Date: 31 January 2026
5. Submit a report on completion of the commissioning or modification of the chosen treatment option, with an updated site-specific disinfection policy, an updated site operating manual and evidence of completion of training required as specified in measure (b)4.
   Date: 30 June 2029
6. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
   Date: 30 November 2024
7. Submit any revisions of the audit strategy produced under measure (c)2.
   Date: Within 1 month of a revision
8. 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
9. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
   Date: 30 June 2030

Further Details of this Notice:

4. Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
5. 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.
6. 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
16 August 2024
Reference: SEW-2024-00004