Current improvement programmes

Notice of Regulation: Rassau/Sirhowy Valley



DŴR CYMRU WELSH WATER: Z7076L45 Rassau / Sirhowy Valley

Z7076L45 Rassau / Sirhowy Valley : Supply System Y8119 Pontsticill High Level / Heads of Valleys

Improvement Programme Database Reference number – DWR 3538


  1. have received a report from Dŵr Cymru Welsh Water (the “Company”) dated 11 March 2015 (the “Report”) which states that there is or has been a significant risk of supplying water from the Rassau / Sirhowy Valley 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 Pontsticill, Carno, Nantybwch and Talybont 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 Pontsticill, Carno, Nantybwch and Talybont 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: 31 March 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: 31 March 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 Pontsticill, Carno, Nantybwch and Talybont works.
    • Implementation of enhanced sampling programme throughout the zone for Fe and Mn to 76 per year.
    • 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:

  • 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: 30 April 2023
    • Delivery of remediation identified in Step (b)5.
      Date: 30 April 2025
    • Initial completion report.
      Date: 31 October 2026
  • Review the risk assessment for Z7076L45 as required by Regulation 27(3) and subsequently submit a revised regulation 28 report.
    Date: 31 July 2025
  • 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 DWR3538
Version 3