Current improvement programmes

Notice of Regulation: Castle Carrock




Assets affected:

Castle Carrock WTW T082
Z001 Castle Carrock
Z002 Carlisle North
Z003 Carlisle South

Legal Instrument Database Reference number: LI/UUT/2018/00003


  1. has received a report from United Utilities Water Limited (the “Company”) dated 21 April 2017 (the “Report”) which states that there is or has been a significant risk of supplying water from Castle Carrock 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 measure[s] for the period specified [in each case]

  1. Continue with catchment management measures and management of the source water and its abstraction.
    Date: Duration of Notice
  2. Maintain existing catchment initiatives with external bodies such as:DEFRA Environment Agency Water – Safeguard Zone for Castle Carrock WTW for Geosmin DEFRA, RSPB ,Eden River Trust and Water Industry groups
    Date: Commencing 2020
  3. Maintain enhanced monitoring of raw water sources for chlorophyll A, geosmin and 2-methylisoborneol (2MIB).
    Date: For duration of this notice
  4. Maintain action trigger levels and appropriate action response as detailed in Castle Carrock WTW algal (taste and odour) management plan.
    Date: For duration of this notice
  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.
    Date: For duration of this notice

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

  1. Catchment investigation to identify high risk areas and possible sources of nutrient causing taste and odour issues working with the Eden Rivers Trust.
    Date: 31 March 2022
  2. Survey on non-owned Geltsdale catchment to verify catchment knowledge and identify high risk areas.
    Date: 31 March 2022
  3. Investigate the possibility of further novel management of Castle Carrock Impounding Reservoirs.
    Date: 30 September 2020
  4. Confirm process solution following investigations into the viability and validation of UV LED technology.
    Date: 30 September 2020
  5. Complete process solution as defined in (b)4 to include either:
    • Refurbishment of the first stage filters and replacement of existing media with Granular activated carbon (GAC)
      Date: 31 January 2023
    • Installation of Ultra Violet (UV) Light Emitting Diode (LED) treatment.
      Date: TBC on completion of (b)4.

(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 in step (c)1
      Date: 31 January 2020
    • Outcome of investigation on management of Castle Carrock impounding reservoir in step (b)3
      Date: 31 October 2020
    • Report on River Eden and Geltsdale Survey Investigations in steps (b)1 and (b)2.
      Date: 30 April 2022
    • Confirmation of the process solution report as defined in step (b)4.
      Date: 31 October 2020
    • Completion of the process solution in step (b)5.
      Date: TBC on completion of step (b)4.
  2. Review the risk assessment for T082 Castle Carrock WTW as required by Regulation 27(4) and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
    Date: 31 March 2023
  3. Submit a satisfactory completion report.
    Date: 29 February 2024

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/2018/00003
Version 1