Dwr Cymru Cyfyngedig – Disinfection Stage Management – onsite assets
Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018
Reference: DWR-2024-00012
Version Number: 1
Water undertaker as appointed under section 6 of The Water Industry Act 1991 (as amended): Dwr Cymru Cyfyngedig, with registered number 02366777 (hereinafter called ‘the Company’).
Assets Affected:
|
Asset Name |
Reference |
|
Abergynolwyn WTW Final |
T600812 |
|
Alaw North WTW Final |
T698096 |
|
Alaw South WTW Final |
T619812 |
|
Alwen WTW Final |
T706211 |
|
Bretton WTW Final |
T706125 |
|
Broomy Hill WTW Final |
T54063 |
|
Builth WTW Final |
T54075 |
|
Cantref WTW Final |
T67151 |
|
Capel Curig WTW Final |
T607832 |
|
Capel Dewi WTW Final |
T122057 |
|
Cefni WTW Final |
T622922 |
|
Cefnllan WTW Final |
T125012 |
|
Court Farm WTW Final |
T320509 |
|
Cwellyn WTW Final |
T603212 |
|
Cwm Dulyn WTW Final |
T628512 |
|
Cwmtillery L.L. WTW Final |
T48143 |
|
Dinas Mawddwy WTW Final |
T612432 |
|
Dolbenmaen WTW Final |
T642112 |
|
Dunfield WTW Final |
T54761 |
|
Eithinfynydd WTW Final |
T637742 |
|
Elan WTW Final |
T54227 |
|
Felindre WTW Final Water |
T792234 |
|
Ffynnon Gaer WTW Final |
T54246 |
|
Garreglwyd WTW Final |
T615242 |
|
Glascoed WTW Final |
T706250 |
|
Gwastadgoed WTW Final |
T625032 |
|
Hirwaun WTW Final |
T303550 |
|
Llan Y Mawddwy WTW Final |
T624722 |
|
Llechryd WTW Final |
T121997 |
|
Llwynon WTW Final |
T67149 |
|
Llyn Conwy WTW Final |
T641822 |
|
Llyswen WTW Final |
T54452 |
|
Lower Carno WTW Final |
T48287 |
|
Mynydd Llandegai WTW Final |
T627432 |
|
Pen Y Cefn WTW Final |
T612652 |
|
Pendine WTW Final |
T122900 |
|
Pontsticill WTW Final |
T67034 |
|
Preseli WTW Final Water |
T123153 |
|
Rhiwgoch WTW Final |
T618212 |
|
Sluvad WTW Final |
T48498 |
|
Strata Florida WTW Final |
T121750 |
|
Talybont WTW Final |
T48562 |
|
Tynywaun WTW Final |
T67089 |
|
Vowchurch WTW Final |
T54684 |
|
Whitbourne WTW Final |
T54712 |
Details of this Notice:
- The Drinking Water Inspectorate (‘the Inspectorate’) has received a set of regulation 28(1) reports, of the Water Supply (Water Quality) Regulations 2018 (‘the Regulations’) from the Company on 21 October 2024, which state that there is or has been a significant risk of supplying water from the water treatment works listed in Annex 1 (and associated assets as applicable) that could constitute a potential danger to human health or could be unwholesome.
- Consequently, this notice is served on the Company by the Inspectorate on behalf of the Welsh Ministers, under regulation 28(4) for the assets listed above, for risks associated with:
|
Hazard/ Hazardous Event/ Parameter |
Example Hazard I D | |
|---|---|---|
|
Turbidity >1 NTU at the point(s) of disinfection and at the disinfection stage(s) discharge point(s). |
Turbidity |
D114566 – Turbidity level greater than 0.5 NTU (50% PCV) within the chlorine disinfection process, affecting efficacy of treatment and disinfection. Potential turbidity risk. |
|
Cryptosporidium in the final water and associated supply zone. |
Cryptosporidium |
D189894 – Risk of Insufficient Protozoan (crypto) log reduction and inability to meet Reg 26 based target. |
|
Manganese >50 µg/L in the final water and associated supply zone. |
Manganese |
D185541, Potential for elevated levels of manganese due to its presence in the raw water, treatment effectiveness or network. |
|
Iron >200 µg/L in the final water and associated supply zone. |
Iron |
D138653, Potential for elevated levels of iron due to its presence in the raw water, treatment effectiveness or network. |
|
Failure of disinfection. |
UV system validation parameters (where applicable), flow, turbidity, pH, free chlorine, Ct10 |
D111511, Failure of disinfection plant (such as storage tanks, dosing lines, control system), loss of or suboptimal disinfection. Potential microbiological risk. |
|
Failure to isolate undisinfected water from supply. |
Microbiological |
D114336 Run to waste capability to prevent non-compliant water leaving the works. Potential microbiological risk. |
- The Company are required to satisfy the following requirements.
The date given is that until or by which the requirements must be maintained or satisfied, as appropriate.
Requirements:
(a) To maintain the following measures for the period specified in each case:
- Continuous online monitoring of turbidity, free chlorine and pH at ‘point of disinfection’, appropriate points within, and at the end of the disinfection stage/process. With appropriate alarms and failsafe shutdowns to ensure compliance with the Regulations and the Company’s Site Specific Disinfection Strategy.
Date: Ongoing for the duration of the notice - Continuous online monitoring of UV system performance validation parameters with appropriate alarms and failsafe shutdowns to ensure compliance with the manufacturer’s validation information and the Site-Specific Disinfection Strategy (method statements) where applicable.
Date: Ongoing for the duration of this notice - Continuous online monitoring of water flow and level in disinfection stage/process sections, where t10 is measured this should be verified with an appropriate flow measurement and level detection, with appropriate alarms and failsafe shutdowns as appropriate for sites where this monitoring is in place. These monitors should be used to provide verification of the Ct10 calculated value.
Date: Ongoing for the duration of this notice - Cryptosporidium monitoring based on the risk informed company strategy.
Date: Ongoing for the duration of this notice - Ensure that turbidity, pH, free chlorine, flow, level and ultra-violet (UV) system performance validation equipment is maintained in-line with manufacturers’ instructions.
Date: Ongoing for the duration of this notice - Operation of all processes within defined operating ranges outlined on the Company’s Site-Specific Disinfection Strategy with appropriate triggers, responses and contingency procedures to meet the requirement of the Regulations.
Date: Ongoing for the duration of this notice - Site-Specific Disinfection Strategies (method statements) will be up-to-date and subject to continuous review, which identify clearly how disinfection is achieved, demonstrated and evidenced at each water treatment works.
Date: Ongoing for the duration of this notice - Maintain contingency plans (including liaison with relevant stakeholders as appropriate) to protect human health.
Date: Ongoing for the duration of this notice
(b) To review, revise or make operational the following measures, by the dates specified in each case:
- Conduct a critical review of the risk of turbidity associated with sediment accumulation and mobilisation within company disinfection stage assets. This should include;
- Investigate and implement measures to ensure turbidity is less than 1 NTU prior to and during the disinfection process, from the point of disinfection monitoring point to the point at which disinfection is complete.
- Assessing the condition of any at-risk tanks and mains / pipework within company disinfection systems and identify any required remedial works to be completed under (b)2.
Date: 31 Dec 2027
- Design and deliver a solution(s) to address any significant risks of 4 or 5 as defined in the DWSP methodology, identified through the completion of the review required under measure (b)1. All other risks identified shall be recorded in the DWSP and appropriate action in line with the DWSP methodology
Date: 31 May 2029 - Develop, review and implement a procedure relating to the regular, controlled automatic or manual conditioning of pipes and cleaning of tanks and other infrastructure. This procedure should cover stepped flow increments with appropriate review and control points up to the maximum flows. Appropriate measures should be taken to assure water quality compliance with regulation 4 requirements within the main and any associated disinfection stage/process assets during these operations.
Date: 31 March 2029 - Conduct a review of all sites in Table 1 and identify whether there is continuous online monitoring to enable the calculation of a live SCADA Ct10 value for each discrete section and for the entirety of the disinfection stage/process with appropriate alarms where this monitoring is in place and failsafe shutdowns where applicable to ensure compliance with the Site-Specific Disinfection Strategies (method statements).
Date: 31 May 2027 - For sites that do not comply with (b)4, develop a programme of work to ensure there is continuous online monitoring to enable the calculation of a live Ct10 value for each discrete section and for the entirely of the disinfection stage/process with appropriate alarms and failsafe shutdowns where applicable to ensure compliance with the Site-Specific Disinfection Strategies (method statements).
Date: 31 December 2027 - Deliver the programme of work (to include installation and commissioning) as developed in (b)5.
Date: 31 March 2029 - Identify all chlorine and/or ultra violet (UV) stages within the disinfection process where upstream or representative online turbidity monitoring is absent.
Date: 31 May 2027 - Where absent, install and commission turbidity monitors with associated communications, alarms and fail-safes as appropriate at a point immediately upstream or representative of all chlorine and/or ultra violet (UV) stages identified in (b)6 and at the end point(s) of disinfection. This should include turbidity monitors upstream of UV systems.
Date: 31 May 2029 - Conduct a critical review of the site operational alarms and fail-safes associated with assuring compliance with the Site-Specific Disinfection Strategy (method statement). The parameters of interest should include, but are not limited to, the UV system validation parameters, turbidity, pH, free chlorine and Ct10.
Date: 31 May 2027 - Design a solution(s) for all risks identified under measure (b)9 and complete any required work to address any significant risks of 4 or 5 as defined in the DWSP methodology.
Date: 31 May 2028 - Conduct a critical review of the risks to consumers associated with an inability to contain and dispose of water arising within the disinfection stage(s)/process that fails, or is likely to fail to meet the requirements of regulation 4(1) and regulation 26. This operation should not compromise the downstream distribution water quality, sufficiency or the environment. The relevant regulation 28 risk lines should be updated where relevant.
Date: 31 May 2027 - Design a solution(s) and develop a programme of work to address the risks identified in (b)11. Where the provision of isolation and run to waste facilities is in progress or deemed not to be practicable appropriate contingency plans and procedures should be produced.
Date: 31 March 2029 - Complete the programme of work, developed in (b)12, to address any significant risks of 4 or 5 as defined in the DWSP methodology. All other risks identified shall be recorded in the DWSP and appropriate action in line with the DWSP methodology
Date: 31 May 2032 - In response to (b)11 and where appropriate for sites with existing or planned run-to-waste facilities, produce and review a user-friendly procedure (step-wise instructions) for running each and all sections of the disinfection stage(s)/process including any final water storage tank(s) to waste in the event of non-compliant water being apprehended at the inlet, within or at the outlet of the disinfection stage/process. This operation should not compromise the downstream distribution water quality, sufficiency or the environment. The procedure should include advice regarding the complete removal of non-compliant water from the system where possible.
Date: 31 July 2027 - For any solutions identified in this notice that have not been resolved and that are to be submitted in Price Review 2029 (PR29), develop a risk based programme of work including timescales.
Date: 31 May 2029
(c) To audit whether the measures have been effective by the following means:
- Define an audit strategy to monitor the effectiveness of the measures specified in sections (a) and (b) at a suitable frequency and in accordance with the DWI audit strategy guidance.
Date: 30 November 2025 - 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 the Treatment Works named 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:
- Provide a progress report annually.
Date: by 31 January each year. - Submit the audit strategy for auditing the effectiveness of the measures, as specified in measure (c)1.
Date: 31 December 2025 - Provide a report, including an action plan to evidence completion of measure (b)1
Date: 31 January 2028 - Provide a report to evidence completion of measure (b)2.
Date: 30 June 2029 - Provide a report confirming and evidencing completion of measures (b)3, including evidence of the completed mains conditioning or cleaning of tanks.
Date: 30 April 2029 - Provide a report confirming and evidencing completion of measures (b)4
Date: 30 June 2027 - Provide a report, including the programme of works and timescales as required in measure (b)5.
Date: 31 January 2028 - Provide a report evidencing completion of the programme of works as required in measure (b)6.
Date: 30 April 2029 - Provide a report identifying the locations where turbidity monitors are missing, as required in measure (b)7.
Date: 30 June 2027 - Provide a report, as required in measure (b)8 evidencing the installation of turbidity monitors.
Date: 30 June 2029 - Provide a report on the critical review of site alarms and fail-safes as required in measure (b)9.
Date: 30 June 2027 - Provide a report and evidence the completed works as required in (b)10. Where any risk is not actioned due to being 3 or below in risk as per DWSP methodology, provide the DWSP risk line(s).
Date: 30 June 2028 - Provide a report on the critical review as required in measure (b)11.
Date: 30 June 2027 - Provide the programme of work to address the risks in (b)11, as required by measure (b)12. Provide evidence of contingency plans where required.
Date: 30 April 2029 - Provide a report evidencing the completion of the programme of works for the significant risks of 4 or 5 as defined in the DWSP methodology, as required be measure (b)13. Provide the DWSP lines for the non-significant risks.
Date: 30 June 2032 - Provide a report and provide the procedure as required by measure (b)14.
Date: 31 August 2027 - Provide the risk-based programme of work including timescales for solutions identified via this notice and submitted in Price Review (2029).
Date: 30 June 2029. - Submit any revisions of the audit strategy produced under measure (c)2.
Date: Within 1 month of a revision - Submit a report in the event that any completed measures of this Notice need to be altered in any way, for any reason.
Date: Ongoing for the duration of this notice - Submit a satisfactory completion report accompanied by a revised regulation 28(1) report with Board level Director sign-off.
Date: 30 June 2033
Further Details of this Notice:
- Any product or substance used as a result of the requirements in this Notice must comply with regulation 31.
- Under regulation 28(6) the Inspectorate, on behalf of the Welsh Ministers, may by notice served on the Company, revoke or vary this Notice.
- 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).
Signed
Nicholas Adjei
Deputy Chief Inspector, on behalf of the Welsh Ministers
29 September 2025
Reference: DWR-2024-00012