Current improvement programmes

Notice of Regulation: Wessex Water Services Ltd – Discolouration


Wessex Water Services Limited: Discolouration

Reference: WSX-2021-00002

Water undertaker as appointed under section 6 of the Water Industry Act 1991 (as amended): Wessex Water Services Limited, with registered number 02366648 (hereinafter called ‘the Company’).

Assets affected:

  • WSXZ44000002 Zone 2 Maundown North
  • WSXZ44000014 Zone 14 Maundown East
  • WSXZ44000016 Zone 16 Fulwood
  • WSXZ44000037 Zone 37 Bowden
  • WSXZ44000038 Zone 38 Devizes
  • WSXZ44000073 Zone 73 Cattistock (no zonal target)
  • WSXZ44000116 Zone 116 Pole Rue
  • WSXZ44000117 Zone 117 Chard Town
  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 dated 2013 to 2021, which states that there is or has been a significant risk of supplying water from the water quality zones listed above (and associated assets as applicable) that 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:

Hazard/Hazardous Event/Parameter

Description of Risks


Consumer Acceptability (discolouration)


Consumer Acceptability (discolouration)


Consumer Acceptability (discolouration)


Consumer Acceptability (discolouration)


Consumer Acceptability (discolouration)

  1. The Company are required to satisfy the following:


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

Date: Ongoing for the duration of this Notice

  1. Undertake regulatory and enhanced monitoring as defined within section (c)1 from treatment works, reservoirs and any water supply zones identified as being at risk of discolouration, including the zones listed within this Notice.
  2. Investigate any failure of a discolouration parameter (Aluminium, Iron, Manganese or Turbidity) and determine root cause.
  3. Record and monitor customer contacts in appropriate detail and, along with water quality data, keep under review to inform the forward programme of work.
  4. Deliver a programme of proactive and reactive flushing work on the distribution network, to manage discolouration risks.
  5. Optimisation of existing treatment processes with particular regard to the removal of Aluminium, Iron and Manganese.

(b) to review, revise or make operational the following measures, by the dates specified in each case:

Short term measures

  1. Develop a discolouration strategy to reduce the risk of discoloured water in water supply zones, which is benchmarked against industry good practice. To include:
    Date: 31 December 2021
    • a. Treatment works
    • b. Service Reservoirs
    • c. Trunk mains
    • d. Zonal network
  2. Develop a dynamic risk assessment methodology for water supply zones, utilising all relevant sources of data and with input from relevant stakeholders, to prioritise zones for further investigation and remedial work to reduce the risk of consumer contacts regarding discoloured water. To include:
    Date: 31 December 2021
    • a. Treatment works
    • b. Service Reservoirs
    • c. Trunk mains
    • d. Zonal network
  3. Develop a discolouration root cause analysis methodology to understand the reasons for discolouration, utilising all relevant sources of data, with input from relevant stakeholders.
    Date: 31 December 2021
  4. Review discolouration data from all sources, complete risk assessments for all zones and prioritise high and medium risk zones for root cause analysis.
    Date: 31 March 2022 and then annually for the duration of the Notice
  5. Undertake a root cause analysis in the zones identified at the top of this Notice and in (b)4, to understand discolouration within the Company’s zones using all available sources of data. The outcome of this analysis should form the basis of the company’s evidence base for the AMP8 business plan submission.
    Date: 30 September 2022 and then ongoing for the duration of the Notice
  6. Using the outputs from the root cause analysis in (b)5, develop a bespoke strategy with timescales for the zones at the top of this notice and all high-risk zones identified in (b)4, to reduce the risks of discolouration to consumers. This should be specific to each zone and include as required:
    Date: 31 December 2022 and then ongoing for the duration of the Notice
    • a. Treatment works optimisation
    • b. Service Reservoir cleaning and risk assessment
    • c. Trunk mains conditioning/remediation
    • d. Distribution modelling, flushing, monitoring, network configuration review and optimisation, mains rehabilitation, abandonment/replacement, standpipe management

Medium term measures

  1. Implement bespoke solutions as identified in (b)6, prioritising zones to an agreed programme with highest risks for discolouration, consumer contacts and consumer acceptability to achieve the following;
    • a. Phase 1 – By 2025 a reduction in consumer contacts for discolouration to below the target of 0.6 per 1000 population regionally and below the individual targets identified in audit strategy for zones listed at the top of the notice.
      Date: 31 December 2024
    • b. Phase 2 – Develop strategy to deliver required work for improvements in discolouration contacts in AMP8, taking into account performance improvements attained in AMP7.
      Date: 31 December 2022
    • c. Agree an AMP8 target for reduction on discolouration contacts regionally (to be a maximum of 0.4 contacts per 1000 population) and for individual zones. The regional target should be in line with the rest of the drinking water industry anticipated average.
      Date: 31 January 2024
    • d. Phase 3 – Implement AMP8 strategy developed in Phase 2 (b)7b. to completion and achieve the targets agreed in (b)7c.
      Date: 31 March 2030

(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 section (a) and (b), to include:
    Date: 2 months after date of issue
    • Individual yearly AMP7 zonal contact targets (contact rate per 1000 population) for the zones identified at the top of the notice, to be a minimum of 25% reduction from 2020 figures.
  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 water supply zones defined in this Notice, or not to so supply unless the specified conditions below are satisfied:

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 by 31 January and against the following milestones:
    Date: Annually by 31 January
    • a) Submit a copy of the audit strategy.
      Date: 3 months after date of issue
    • b) Submit a copy of the discolouration strategy developed in (b)1.
      Date: 31 January 2022
    • c) Provide a report detailing the dynamic risk assessment methodology developed in (b)2.
      Date: 31 January 2022
    • d) Provide a report detailing the root cause analysis methodology developed in (b)3.
      Date: 31 January 2022
    • e) Provide a report detailing which zones will be prioritised for root cause analysis in (b)4.
      Date: Annually by 30 April
    • f) Provide a report into the outputs of the root cause analysis and the bespoke solutions identified in (b)5.
      Date: 31 January 2023
    • g) Provide an interim report of the work completed for the notice to date and confirm the company has met the phase 1 target as defined within (b)7.
      Date: 31 January 2025
    • h) Provide a copy of the discolouration strategy for AMP8 as defined in (b)7.
      Date: 31 January 2023
    • i) Provide a report to confirm the agreed target for reduction in discoloured water contacts and the strategy for AMP8, as defined within (b)7.
      Date: 28 February 2024
    • j) Provide a report to confirm the company has met the phase 3 target as defined within section 3(b)7.
      Date: 30 April 2030
  2. Submit a report in the event that any completed measure of this Notice needs to be altered in any way for any reason.
    Date: As required for the duration of the Notice
  3. Review the risk assessments for the zones listed within Annex A as required by Regulation 27(4) and subsequently submit a revised regulation 28 report accompanied by a signed board level declaration.
    Date: From time to time, as required, and by 21 April 2025 and by 21 April 2030.
  4. Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
    Date: 30 April 2031

  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).

Deputy Chief Inspector, on behalf of the Secretary of State for Environment, Food and Rural Affairs
30 July 2021
Reference: WSX-2021-00002
Version 1