Current improvement programmes

Notice of Regulation: Mitchells Water Treatment Works




Assets affected:

  • T072- Mitchells WTW
  • Z102- Mitchells Water Supply System

Legal Instrument Database Reference number: LI/UUT/2018/00005


  1. has received a report from UNITED UTILITIES WATER LIMITED (the “Company”) dated 30 August 2017 (the “Report”) which states that there is or has been a significant risk of supplying water from Mitchells WTW that could be unwholesome.
  2. GIVES NOTICE to the Company under regulation 28(4) of the Water Supply (Water Quality) Regulations 2016 (as amended) that it must satisfy the following requirements:

For risks associated with:

  • Taste and Odour – Raw water quality outside process design envelope resulting in taste and odour issues


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

Date: Duration of the notice

  1. Continue catchment management measures including working with tenants to reduce nutrient loading and management of source water and abstraction.
  2. Maintain existing catchment initiatives with external bodies such as: DEFRA Water Industry Taste and Odour management group.
  3. Maintain enhanced monitoring of raw water sources for chlorophyll A, geosmin and 2-methylisoborneol (2MIB).
  4. Maintain action trigger levels and appropriate action response as detailed in Mitchells WTW algal (taste and odour) management plan.
  5. Instigate temporary mobile powdered activated carbon dosing on detection of geosmin and/or 2-MIB is identified above the trigger levels documented in the algal management plan.

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

  1. Complete catchment investigation to identify high risk areas and possible sources of nutrient causing taste and odour issues The Company will work with the EA to pursue the status as designated a Safeguard Zone for algae.
    Date: 31 March 2022
  2. Confirm process solution following investigations into the viability and validation of UV LED technology.
    Date: 30 September 2020
  3. Complete and commission process solution as defined by (b)2. Solution to include either:
    • Refurbishment of the first stage filters and replacement of existing media with Granular activated carbon (GAC)
      Date: 30 September 2022
    • Installation of Ultra Violet (UV) Light Emitting Diode (LED) treatment
      Date: TBC

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

  1. Define a strategy for auditing the effectiveness of the above measures, to include raw water monitoring and treated water monitoring when in supply.
    Date: 31 December 2019
  2. Implement the audit strategy outlined in (c)1 until revocation of the Notice.
    Date: 01 April 2020

(d) not to supply water for regulation 4(1) purposes from


(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 annually by 31 January and against the following milestones:
    • Audit Strategy to be submitted
      Date: 31 January 2020
    • Report on catchment investigation regarding safeguard zone to EA in step (b)1
      Date: 30 April 2022
    • Confirmation of the process solution in step (b)2
      Date: 31 October 2020
    • Completion of the process solution in step (b)3.
      Date: TBC on completion of step (b)2
  2. Review the risk assessment for T070 Mitchells WTW as required by Regulation 27(4) or and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
    Date: 30 November 2022
  3. Submit a satisfactory completion report
    Date: 30 October 2023

Failure by the Company to comply with this Notice may result in enforcement proceedings under section 18 of the Act.

Signed by authority of the Secretary of State
Milo Purcell
Deputy Chief Inspector
10 April 2019
DWI ref: LI/UUT/2018/00005
Version 1