Notice of Regulation: Whittle Dene Treatment Works

Notice Under Regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended)

Northumbrian Water Limited: Whittle Dene Treatment Works

Reference: NES-2020-00002

Version Number: 3

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Northumbrian Water Limited, with registered number 02366703 (hereinafter called ‘the Company’).

Assets affected:
Whittle Dene Water Treatment Works (T0700351)

  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 on 08 November 2019, which states that there is or has been a significant risk of supplying water from Whittle Dene Treatment Works that could constitute a potential danger to human health.
  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:


Risk ID

Cryptosporidium Oocysts (Confirmed)

E. coli (Confirmed)

Total Coliforms (Confirmed)




  1. The Company are required to satisfy the following:


(a) to maintain the following measures for the period specified:

  1. To ensure that wholesome water is supplied to consumers at all times, in accordance with the requirements of Regulation 4.
    Date: Ongoing for duration of Notice
  2. Continuous sampling for Cryptosporidium oocysts on final water and monitoring on the raw water in line with the Cryptosporidium monitoring strategy.
    Date: Ongoing for duration of Notice
  3. Operation of all processes within defined operating ranges with appropriate triggers, responses and contingency procedures.
    Date: Ongoing for duration of Notice
  4. Ensure all critical treatment process stages are not bypassed. Adequate risk assessment and authorisation is required if bypass is demonstrably necessary.
    Date: Ongoing for duration of Notice
  5. Ensure the works control and shutdown system is operational and that monitors are calibrated at the predefined frequencies.
    Date: Ongoing for duration of Notice
  6. Ensure any new risks identified are assessed in accordance with the Company’s Drinking Water Safety Plan (DWSP) methodology and submitted to the Inspectorate under Regulation 28.
    Date: Ongoing for duration of Notice
  7. Up to date Site Operating Manual defining normal operating ranges, triggers, response and contingency procedures with controlled update and review programmes.
    Date: Ongoing for duration of Notice
  8. Water quality response procedures for investigation of contraventions including process optimisation and reporting.
    Date: Ongoing for duration of Notice
  9. Maintain contingency plans to protect human health in the event of a risk to human health associated with drinking water quality, which should include liaison with local authorities and Public Health England to agree any actions needed to protect human health and issuing of advice to consumers, where required.
    Date: Ongoing for duration of Notice

(b) to review, revise and/or make operational the following measures, by the date specified below:

  1. Complete a catchment review to identify any relevant catchment management measures that can be implemented to reduce the risks from Cryptosporidium.
    Date: Complete
  2. Implement catchment management measures identified from (b)1.
    Date: 31 March 2022
  3. Review and revise procedures for abstraction and reservoir management in relation to Cryptosporidium and turbidity monitoring data.
    Date: Complete
  4. Complete a gap analysis of clarification and rapid gravity filtration performance and compliance with Badenoch and Bouchier recommendations at Whittle Dene water treatment works. This must include the following;
    Date: Complete
    • Consideration of maximum design capacities and operational envelopes and treatment stage suitability. The works should be able to handle reasonably anticipated peak turbidity and colour loadings
    • Review of filter backwash sequence and air-scour system initiation and controls to minimise effects on final water quality during sequence and upon start-up
    • Review of backwash water recycling to works inlet including the controls on supernatant not exceeding 10 NTU when returned to head of the works
    • Investigate options to improve slow start and start-up to waste procedures following backwashing to fully mitigate risks to the works
    • Filter media condition and depth assessment.
    • Review of online continuous monitoring of turbidity on each filter outlet
    • Works shutdown and restart procedures
  5. Develop an action plan from the gap analysis findings ((b)4.) for Whittle Dene water treatment works.
    Date: Complete
  6. Deliver action plan defined in (b)5. for Whittle Dene treatment works.
    Date: 31 December 2021
  7. Update water quality training modules for staff including production operators, water quality scientists and water supply managers to include awareness of the potential impacts changes in the upstream catchment and raw water can have on final water wholesomeness.
    Date: Complete
  8. Complete a tank inspection and clean of Whittle Dene water treatment works contact tanks.
    Date: Complete

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

  1. Define and keep under continuous review an audit strategy to monitor the effectiveness of the above measures.
    Date: 1 month after Notice served
  2. Implement the audit strategy defined in (c)1.
    Date: For the duration of the Notice.

(d) not to supply water for regulation 4(1) purposes from Whittle Dene water treatment works unless the conditions specified below are satisfied:


(e) to provide the following information in the time and manner specified below to enable monitoring of progress towards the mitigation of the risk of supplying water that would constitute a potential danger to human health:

  1. Provide a progress report at key milestones:
    • Confirm the findings from the catchment review any relevant catchment management measures being undertaken in response to the review.
      Date: Complete
    • Provide confirmation of abstraction and reservoir management review completion (outlined in (b)3).
      Date: Complete
    • Confirm completion of the gap analysis in (b)4. and submit the associated action plan outlined in (b)5.
      Date: Complete
    • Confirm update to water quality training modules outlined in (b)7.
      Date: Complete
    • Confirm all action plan items completed ((b)6.) and provide details of any review or best operational practice evaluation outcomes.
      Date: 31 January 2022
    • Report to confirm details of the strategy for auditing effectiveness of the measures as specified in section (c).
      Date: 2 months after Notice served
    • Regular submission of progress
      Date: Annually on 31 January
  2. Review the risk assessment for Whittle Dene Works and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
    Date: Ongoing until revocation of Notice
  3. Submit a satisfactory completion report.
    Date: 30 April 2023

  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
02 March 2022
DWI Reference: NES-2020-00002
Version 3

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