Dwr Cymru Cyfyngedig – Disinfection Stage Management
Notice under regulation 28(4) of the Water Supply (Water Quality) Regulations 2018
Reference: DWR-2023-00012
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 |
|---|---|
|
Bryncrug Penybont WTW Cilfor WTW Llannerch Park WTW Bryn Cowlyd WTW Bala WTW Trecastell WTW Brecon Penycrug WTW Brecon St Davids WTW Leintwardine WTW Pilleth WTW Maerdy Nantybwch WTW Mayhill WTW Cefn Dryscoed WTW Crai WTW Bontgoch WTW Bryngwyn WTW Bolton Hill WTW |
T604612 T641622 T706162 T612522 T706122 T706660 T54090 T54092 T54391 T54666 T67358 T320200 T54494 T79177 T79086
T77092 T120030 |
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 12 October 2023, 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 ( all examples Penybont WTW Final unique IDs) | |
|---|---|---|
|
Turbidity >1 NTU at the point(s) of disinfection, any critical discrete t10 section monitoring points within the disinfection stage(s) and at the disinfection stage(s) discharge point(s). |
Turbidity |
D196969, Delivery pipework to Final water tank – Potential Turbidity risk |
|
Cryptosporidium in the final water and associated supply zone. |
Cryptosporidium |
D168980, Off-site FWT Escuan. Potential for Presence of Cryptosporidium. |
|
Manganese >50 µg/L in the final water and associated supply zone. |
Manganese |
D125947, 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 |
D125946, 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 |
D110572, Failure of disinfection plant (e.g. storage tanks, dosing lines, control system), loss of or suboptimal disinfection. Potential microbiological risk. |
|
Failure to isolate undisinfected water from supply.
|
Microbiological |
D110652, Run to waste capability to prevent non-compliant water leaving the works. Potential microbiological risk. |
3. 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 in the final water and “point of disinfection” monitoring point(s) with appropriate alarms, for sites where this monitoring is in place, and failsafe shutdowns where applicable.
Date: Ongoing for the duration of this notice - Continuous online monitoring of water flow in treated water mains transferring water from a water treatment works site to any off-site contact and/or final water storage tank(s) with appropriate alarms and failsafe shutdowns as appropriate for sites where this monitoring is in place. These monitors should be used to provide live verification of the Ct10 calculated value for these mains.
Date: Ongoing for the duration of this notice - Operation of all processes within defined operating ranges with appropriate triggers, responses and contingency procedures.
Date: Ongoing for the duration of this notice - Continuous monitoring for Cryptosporidium in the final water based on the risk informed company audit strategy.
Date: Ongoing for the duration of this notice - Ensure that turbidity, pH, free chlorine, flow and ultra-violet (UV) system performance validation monitoring equipment is maintained in-line with manufacturers’ instructions.
Date: Ongoing for the duration of this notice - Up-to-date and subject to continuous review, site specific disinfection policies, which identify clearly and unequivocally how disinfection is achieved at each water treatment works.
Date: Ongoing for the duration of this notice - Continuous online monitoring of free chlorine in the final water and “point of disinfection” monitoring point(s) with appropriate alarms and failsafe shutdowns to ensure compliance with the site specific disinfection policies.
Date: Ongoing for the duration of this notice - Continuous online monitoring of pH in the final water and “point of disinfection” monitoring point(s) with appropriate alarms and failsafe shutdowns to ensure compliance with site disinfection policies.
Date: Ongoing for the duration of this notice - 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 with appropriate alarms where this monitoring is in place and failsafe shutdowns where applicable to ensure compliance with the site-specific disinfection policies.
Date: Ongoing for the duration of this notice - Continuous online monitoring of UV system performance validation parameters with appropriate alarms and failsafe shutdowns to ensure compliance with the site disinfection policies where applicable.
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.
Date: 30th September 2024 - Design a solution to address any risks identified through the completion of the review required under measure (b)(1). This should include;
- Assessing the condition of any at-risk tanks and treated water mains within company disinfection systems and completing any required remedial works.
- Develop, review and implement a procedure relating to the regular, controlled automatic or manual conditioning of said mains. This procedure should cover stepped flow increments with appropriate review and control points up to the maximum and/or worst case treated water flows.
- Appropriate measures should be taken to assure water quality compliance with regulation 4 requirements within the main and any associated disinfection stage assets/ the offsite contact tank(s) during these operations.
Date 28th February 2025
- Identify all discrete sections of the disinfection stage i.e. ultra violet disinfection systems and those sections of the chlorination stage with separate t10 calculations where upstream online turbidity monitoring is absent.
Date 30th September 2024 - Where absent, install and commission turbidity monitors with associated communications, alarms and fail-safes as appropriate at a point immediately upstream of all the discrete sections of the disinfection stage(s) identified in b3 and at the end point(s) of disinfection.
Date: 31st May 2025 - Investigate and implement any required measures to ensure the online continuous turbidity monitors at the point of disinfection, within and at the end point of disinfection, can verify the actual turbidity levels of the water, intended for regulation 4(1) purposes at these points.
Date: 30th September 2025 - Investigate and implement measures to ensure turbidity is less than 1 NTU prior to and during the disinfection stage, from the point of disinfection monitoring point to the point at which disinfection is complete.
Date: 30th September 2025 - Where absent, install and commission flow meters with associated alarms and fail-safes on treated water mains transferring water from water treatment works to offsite tank(s) used in the disinfection stage for the purposes of (a)(2).
Date: 31st May 2025 - Conduct a critical review of the site operational alarms and fail safes associated with assuring compliance with the site-specific disinfection policies. The parameters of interest should include, but are not limited to, the UV system validation parameters, turbidity, pH, free chlorine and Ct10.
Date: 30th September 2024 - Design a solution(s) and schedule of work to address any risks identified under measure b(8).
Date: 28th February 2025 - Implement the solution(s) according to the schedule of work identified in b(9).
Date: 31st May 2025 - 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) that fails to meet the requirements of regulation 4(1).
Date: 30th September 2024 - Design a solution(s), where practicable, to address any risks identified through the completion of the review required under measure (b)(11). Where the provision of isolation and run to waste facilities is deemed not to be practicable appropriate contingency plans and procedures should be produced.
Date: 28th February 2025 - 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) including any offsite contact tank(s) or 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. This operation should not compromise the downstream distribution water quality or sufficiency. The procedure should include advice regarding the complete removal of non-compliant water from the system where possible.
Date: 30th September 2025
(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: 31 July 2024 - 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: 30 August 2024 - Submit a report confirming and evidencing completion of measures (b)1, (b)3, (b)8 and (b)11.
Date: 31 October 2024 - Submit a report confirming and evidencing completion of measures (b)2, (b)9 and (b)12.
Date: 31 March 2025 - Submit a report confirming and evidencing completion of measures (b)4, (b)7 and (b)10.
Date: 30 June 2025 - Submit a report confirming and evidencing completion of measures (b)5, (b)6 and (b)13.
Date: 31 October 2025 - 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: 31 October 2025
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
21 May 2024
Reference: DWR-2023-00012