Notice of Regulation: Yorkshire Water Services Limited – Haisthorpe WTW Nitrates

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

Reference: YKS-2023-00006

Version Number: 1

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Yorkshire Water Services Limited, with registered number 02366682 (hereinafter called ‘the Company’).

Assets Affected:

  • Haisthorpe WTW (T2694270)

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 October 2023 which states that there is or has been a significant risk of supplying water from Haisthorpe 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:

Description of Risk

Hazard/ Hazardous Event/ Parameter

Hazard I D

Enhance risk of raised levels of nitrate due restrictions on blending



Table 1: 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. Continuation of ongoing catchment management investigations. Engaging with key stakeholders as necessary to reduce risk of impact on groundwater quality. 
    Date: Ongoing for the duration of this Notice
  2. Operation of water treatment assets to ensure mixing of individual groundwater source in order to achieve reduced nitrate levels in supply. 
    Date: Ongoing for the duration of this Notice
  3. Monitoring of raw and treated water quality in line with a defined Audit Strategy. 
    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 the chosen solution and provide an outline design for the proposed solution for addressing the risks of nitrate in water supplied from Haisthorpe WTW.
    Date: 31 May 2025
  2. Provide a detailed design of the proposed solution that was confirmed in (b)1.
    Date: 30 April 2026
  3. Install, commission, and verify through testing, the confirmed solution. Complete the construction, installation and commissioning of the chosen solution, designed under measure (b)2. Commissioning must include the following to account for the changes made:
  • An appropriate maintenance regime for any installed processes;
  • Full integration of the new (or modified) processes into the site control and monitoring systems.
  • Updating of the Site-Specific Disinfection Policy and any associated site-specific procedures;
  • Updating of the Site Operating Manual and removal of all out-of-date material from circulation; and
  • Provisions of adequate training for all relevant personnel on the operation, repair and maintenance of the installed (or modified) process and the revised procedures, policies and manual.

Date: 30 September 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 January 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 Haisthorpe 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. Completion of investigations, pilot trials and development of outline design. 
    Date: 30 June 2025
  3. Completion of detailed design of the proposed solution.
    Date: 31 May 2026
  4. Install, commission, and verify through testing, the confirmed solution.
    Date: 31 October 2027
  5. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: 29 February 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: 31 October 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
22 November 2023
Reference: YKS-2023-00006

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