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Yorkshire Water Services Limited – Tophill Low Cryptosporidium AMP7

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

Reference: YKS-2018-00001

Version Number: 5

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:

  • Tophill Low No. 2 WTW – T2698270
  • Leven – YSAI00162810

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 2 and 26 March 2021 (originally 2 November 2017), which states that there is or has been a significant risk of supplying water from Tophill Low 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


Failure of treatment process to prevent Cryptosporidium entering supply.

C111 – Cryptosporidium

45018


Failure of treatment process to remove taste and odour causing compounds from raw water and failure of PAC dosing.

A003 – Odour

40360


Failure of treatment process to remove taste and odour causing compounds from raw water and failure of PAC dosing.

A004 – Taste

43939

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.

Requirements:

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

  1. Continue weekly monitoring and regular review of raw water quality at the abstraction points and works inlet for phytoplankton, phosphate, Geosmin, 2-methylisoborneol (2-MIB), nitrate, ammonia, and Cryptosporidium. Keep online turbidity trends under constant review. Adhere to the Tophill Low 2-MIB and Geosmin Escalation procedure (Annex C in MIB & Geosmin Mitigation Plan), ensuring appropriate enhanced monitoring is undertaken when Level 2/3/4 triggers are reached.
    Date: Ongoing for the duration of this Notice
  2. Optimise existing processes to minimise the risk of taste and odour causing compounds (2-MIB and Geosmin) entering the final water and maximise the removal of oocysts. Maintain adherence to the Tophill Low 2-MIB and Geosmin Escalation procedure (Annex C in 2-MIB & Geosmin Mitigation Plan), to ensure that the appropriate PAC dose is applied considering the raw water quality.
    Date: Ongoing for the duration of this Notice
  3. Monitor weekly treated water for Cryptosporidium, 2-MIB, Geosmin, and microbiological parameters.
    Date: Ongoing for the duration of this Notice
  4. Keep under continuous review the appropriateness of raw water quality parameters, sampling frequencies, and trigger values in relation to PAC dosing at the works to ensure that the dosing is as proactive as possible.
    Date: Ongoing for the duration of this Notice
  5. Continue to review and trial the opportunities for catchment management activities to reduce the risk of deterioration of raw water quality, including pursuing alternative abstractions from West Beck with the Environment Agency and Natural England, and implement those measures where permitted.
    Date: Ongoing for the duration of this Notice
  6. Continue to monitor key service reservoirs downstream of Tophill Low works, with weekly quantitative taste and odour samples and monitor the network downstream of Tophill Low as specified in the Tophill Low 2-MIB and Geosmin Escalation procedure (Annex C in Tophill Low WTW 2-MIB & Geosmin Mitigation Plan).
    Date: Ongoing for the duration of this Notice
  7. Regularly monitor and review 2-MIB and Geosmin concentrations between each stage of the treatment process to ensure that treatment processes are optimised.
    Date: Ongoing for the duration of this Notice
  8. Continue daily taste and odour panels at Tophill Low works to mitigate risk of consumer impact.
    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 additional removal of 2-MIB and Geosmin, improved removal of Cryptosporidium oocysts, and improved disinfection facilities, following engineering and process reviews, and, where required, pilot trials.
    Date: Complete
  2. Provide a detailed design of the proposed solution that was confirmed in (b)1.
    Date: Complete
  3. Install, commission and verify through testing, the confirmed solution.
    Date: 30 September 2025

(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 Tophill Low 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, as specified in (b)1.
    Date: Complete
  3. Completion of detailed design of the proposed solution, as specified in (b)2.
    Date: Complete
  4. Completion of installation and commissioning of the chosen solution, as specified in (b)3.
    Date: 31 October 2025
  5. Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
    Date: Complete
  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 2026

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).

Signed

Nicholas Adjei
Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
18 March 2025
Reference: YKS-2018-00001 v5

 

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