Current improvement programmes

Notice of Regulation: Llyswen




Z2054H24 Llyswen : Supply System Y8105 Llyswen

Improvement Programme Database Reference number – DWR 3533


  1. have received a report from Dŵr Cymru Welsh Water (the “Company”) dated 7 March 2015 (the “Report”) which states that there is or has been a significant risk of supplying water from the Llyswen zone that could constitute a potential danger to human health.
  2. GIVE NOTICE to the Company under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018 that it must satisfy the following requirements:

For risks associated with:

  • Discolouration and associated customer acceptability due to the condition and operation of the network system.


(a) to maintain the following measures for the period specified

  1. Regulatory sampling of water at Llyswen water treatment works and at customers’ taps.
    Date: Ongoing
  2. Monitoring, tracking and reporting customer contacts.
    Date: Ongoing
  3. Responding as required to any PCV failure or customer contact in line with company procedures. Carry out an investigation to determine the root cause of the failure and identify any remedial measures required to prevent a recurrence.
    Date: Ongoing
  4. Liaison with local and public health authorities as appropriate.
    Date: Ongoing
  5. Review risk assessments for customer contacts and update regulation 29 report.
    Date: Ongoing

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

  1. Complete Distribution zonal study (DZS) including formulating the methodology for mitigating discolouration risk in this zone.
    Date: 31 March 2017
  2. Ensure optimisation Llyswen works with 95 percentile less than 20% PCV.
    Date: Ongoing
  3. Confirmation of programme of work identified through the DZS following cost benefit for customer acceptability.
    Date: 30 September 2023
  4. Confirmation of success criteria for demonstration of benefit in delivering the proposed programme of work including commencement dates and timescale for demonstration of benefit.
    Date: 30 September 2023
  5. Delivery of programme of work as identified through DZS in Step (b)3 above.
    Date: 31 March 2025

(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 the following by 29 February 2016;
    Date: Completed
    • Monitoring of iron and manganese levels in samples taken Llyswen works.
    • Implementation of enhanced sampling programme throughout the zone for Fe and Mn to 24 and 12 per year respectively.
    • Review of customer contacts on quarterly basis to measure and monitor change and if necessary escalate remediation as appropriate.
    • Drinking Water Safety Plan and regulation 29 reports updated in line with any new information arising.
    • Review programme of work and delivery timescales to address priority areas of customer acceptability following updated information.
    • Validate benefits delivered against benefits criteria set.
    • Technical reports for preferred solutions where choices are available.
    • Commissioning, completion and handover certificates for all work carried out in line with the programme as defined in step (b)3.
  2. Implement the audit strategy outlined in (c)1, keep under review, and resubmit when subject to change.
    Date: Until revocation of this Notice

(d) N/A

(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:
    • Provision of the output from DZS as indicated in Step (b)1.
      Date: 30 April 2017
    • Provision of the programme of remediation work arising from DZS and criteria for benefit setting as indicated in Step (b)3 (1 month after medium term measure date).
      Date: 31 October 2023
    • Delivery of remediation identified in Step (b)5.
      Date: 30 April 2025
    • Initial completion report.
      Date: 31 October 2026
  2. Review the risk assessment for Z2054H24 as required by Regulation 27(3) and subsequently submit a revised regulation 28 report.
    Date: 31 July 2025
  3. Submit a satisfactory completion report.
    Date: 31 October 2027

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 Welsh Ministers,
Milo Purcell
Deputy Chief Inspector
30 March 2020
DWI ref DWR3533
Version 3