Notice of Regulation: South West Water – Discolouration




Legal Instrument Database Reference number: SWT-2018-00004


  1. has on 20 September 2018 received a report from South West Water (the “Company”) dated 20 September 2018 (the “Report”) which states that there is or has been a significant risk of supplying water from a number of water supply zones 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:

  • Consumer contacts relating to discolouration/appearance of supplies


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

  1. Undertake regulatory and enhanced monitoring from treatment works and the water supply zones identified as being at risk of discolouration.
    Date: Ongoing for the duration of this notice
  2. Investigate any failure of the standard and record and monitor customer contacts in appropriate detail and trend data to inform the forward programme of work.
    Date: Ongoing for the duration of this notice
  3. Deliver a programme of planned flushing, based on WQ monitoring data/consumer contact rates and patterns/risk assessment.
    Date: Ongoing for the duration of this notice
  4. Undertake reactive flushing following consumer contacts; events or water quality failures.
    Date: Ongoing for the duration of this notice
  5. Investigate the need and extend where appropriate the number of trunk main conditioning schemes.
    Date: Ongoing for the duration of this notice
  6. Optimisation of existing treatment processes with particular regard to removal of manganese and other parameters relevant to discolouration.
    Date: Ongoing for the duration of this notice
  7. Maintain a risk based programme of service reservoir inspection and cleaning.
    Date: Ongoing for the duration of this notice

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

Short term measures

  1. Determine the Water Supply Zones to be prioritised in this notice, following a review at the start of AMP7 when the impacts of existing notice have been realised and annually thereafter.
    Date: 30 November 2019
  2. Deliver an operational flushing plan, targeting the highest risk zones each year using a dynamic risk-based approach to determine flushing priorities.
    Date: Ongoing until 31 December 2024

Medium term measure

  1. Develop a further list of candidate trunk main conditioning schemes and deliver them at a pace of 5 per year.
    Date: Ongoing until 31 December 2024

Long term measures

  1. Complete enhanced operational flushing as defined in step (b)1 to achieve (in combination with other measures set out below) a target level of <1.2 contact per 1000 population regionally by the end of the AMP.
    Date: 31 December 2024
  2. Complete mains renewal schemes identified during PR19 planning process.
    Date: 31 December 2024
  3. Continue regional implementation of trunk main conditioning as identified in section (b)3.
    Date: Ongoing until revocation of notice

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

  1. Confirm the strategy for auditing the effectiveness of the above measures.
    • Trunk main conditioning and DOMS flushing schemes delivered against plan.
      Date: 31 January 2020
    • Enhanced water quality monitoring for discolouration parameters including; iron, manganese and turbidity.
      Date: For the duration of this notice
    • Individual water supply zone consumer contact rate below 1.5 per 1000 population following completion and implementation of above measures.
      Date: By 31 December 2024
    • Regional consumer contact rate < 1.2 per 1000 population following completion and implementation of above measures.
      Date: By 31 December 2024
  2. Implement the audit strategy outlined until this Notice is revoked.
    Date: Ongoing for the duration of this notice

(d) not to supply water for regulation 4(1) purposes from the water supply zones specified, 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 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:
    Date: On-going
    • Complete a review of which zones will be prioritised for this scheme, based on results from previous notices, and the results of previous discolouration strategies.
      Date: 31 October 2019 and for each year of the notice
    • Completion of planning, design and procurement arrangements
      Date: 31 January 2020
    • Completion delivery of the AMP7 long term flushing, trunk main conditioning and mains replacement programmes
      Date: 31 March 2024
  2. Submit any revisions of the audit strategy produced under measure (c)1.
    Date: Within 1 month of a revision.
  3. Submit a report in the event that any completed measure of this Notice needs to be altered in any way, for any reason.
    Date: Ongoing for the duration of this notice
  4. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 31 December 2025

  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
06 January 2022
DWI ref: LI/SWT/2018/00003
Version 2

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