Dwr Cymru Cyfyngedig: Regulation 27 Methodology and Methodology Application

Notice under regulation 27(4) of the Water Supply (Water Quality) Regulations 2018

Reference: DWR-2024-00004

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:

• Whole company

Details of this Notice:

1. This Notice is served on the Company by the Drinking Water Inspectorate on behalf of the Welsh Ministers, under regulation 27(4) of the Water Supply (Water Quality) Regulations 2018 for the assets listed above, for risks associated with the company’s drinking water safety plan methodology.

Requirements:

2. The Company are required to satisfy the following:

(a) Carry out a risk assessment:

Not applicable.

(b) Review of a risk assessment:

1. Carry out a critical review of the risk assessment methodology taking into account specific findings detailed below (1a to 1k) and a gap analysis against DWI DWSP Guidance (Information Letter 04-2025-DWSP Guidance).
   
   a) Hazard identification and general approach:

1. Update the methodology to identify all asset types that are relevant for risk assessment, and at which stage each type of asset is reported against within regulation 28 reports. This should include how seasonal changes are managed.
2. Update the methodology to include sufficient details explaining how the risk assessments are undertaken by stage, including a full list of source documentation. 
3. Update the methodology document to include details of how risks with long term risk statuses are processed and managed, including those rejected from the investment system.  
4. Update the methodology to provide clear details on how sample points and sample results relate to risk assessments by stage (for example, sample points are abstraction points but are used for catchment assessments as the methodology does not use an Abstraction stage).   
5. The DWSP methodology document should include a description of the company’s interpretation and use of DWI categories, including ensuring category A risks have appropriate control measures as defined by the DWI definitions of hazard categories.  
6. Ensure that the use of hazardous events and the hybrid approach is clearly defined in the methodology document. Where grouped hazards are used, provide the link to individual parameters within the methodology document.
7. Include details of how the carried forward process works as part of the drinking water safety plan methodology,
8. Include within the methodology document how microbiological parameters are reported.  
9. Develop a suitable risk assessment for risks which cannot be monitored for with sampling, such as pharmaceuticals. 
10. Include a robust pesticide assessment within the drinking water safety plan methodology, which may need to be developed.  
11. Ensure all hazardous events have a suitable range of hazards associated with them. 
12. Define how hazards and hazardous events are allocated to assets, and how updates are made to these lists. 
13. An overview of the hazardous events, including hazardous events specific to asset health assessed at each stage in the supply system should be included within the company’s DWSP methodology.  
14. Review the use of generic hazardous events and hazards to ensure the use of hazardous events and hazards is appropriate for the stage and asset.  
15. Assess risks using a hazardous event basis and provide clear details of how these are subsequently reported under a parameter or hybrid basis, by stage. 
16. Document how the company defines and processes low likelihood, high consequence events.  
17. Develop a process for assessing risks the company does not have full control over, including the assigning a DWI category, scoring, and reporting. 
18. Demonstrate a clear link between the service reservoir inspection reports and hazardous events within the drinking water safety plan methodology. This includes where defects are noted.

b) Scoring

1. Clearly define what different scoring systems exist and how they apply on a stage and/or asset/hazardous event basis and include this information (and the matrices) in the methodology document, ensuring risk scoring matrices are available for all hazardous events at all assets and for all parameters.
2. Include descriptions of pre-likelihood scoring in the methodology document, and be clear where the scores do not refer to the risk without control measures in place (and therefore not a direct comparison to post-control measure scores).
3. Update the methodology to detail how risks can be higher at the post-control score.
4. Extend severity scores and the documentation regarding parameter scoring to include parameters which are not in Schedule 1 or Schedule 2 of the Water Supply (Water Quality) Regulations 2018.
5. Define how the hybrid approach of parameters and some hazardous events is used to produce an overall parameter risk score per asset.
6. Include details of local knowledge of risk within the methodology document, and how this influences scoring criteria.
7. Ensure no risk is defined on data alone, unless the reasoning is clearly specified within the drinking water safety plan methodology document.
8. For catchment characterisation, ensure that a single risk point of sufficient severity would highlight risk adequately.
   

c) Control Measure

1. Update control measures to ensure they are specific for the asset, hazardous event, and hazard being assessed.
2. Review how risks with control measures are scored to ensure that how well the control measure is functioning is taken into account in the post-control measure score.

d) Reporting

1. Provide details in the methodology regarding what an annual risk review encompasses and how the risk review is logged in the system and how this is reflected in the regulation 28 reports submitted to the Inspectorate.
2. Include a description of how each stage is reported, in terms of hazardous events and associated parameters, and what this encompasses, within the methodology document.
3. Include details in the methodology document demonstrating how regulation 28 reports received from other companies are translated to the company’s methodology.

e) Update Catchment risks:

1. Clearly define the catchment scoring and reporting conditions for each hazard/hazardous event, updating the methodology from specifying a parameter-only approach, where this is not used. 
2. Ensure specific catchment hazardous events are clearly mapped and not present under generic hazards such as nutrients or ammonia, so the link between hazardous events and hazards is clear.  
3. Ensure that private and observation borehole assets are included within the risk assessment for the Catchment.  
4. Ensure microbiological risks of slurry application are considered at the Catchment stage.

f) Update Abstraction risks:

1. Review hazardous events relating to asset condition to ensure that all hazards are adequately covered, in addition to No Supply (H063).
2. Review Abstraction stage risks deemed not in the company’s control.

g) Update Treatment risks:

1. Update risk assessments to include the risks of manganese breakthrough on filters.
2. Update hazardous events/risk questions for UV to include UV bulb breakage, run time, on/off cycles, and other performance factors. 
3. Include pH and conductivity within risk assessments and ensure that appropriate hazardous events are created for these at the Treatment stage, to reflect their criticality to the water treatment process. 
4. Update the risk assessments to account for hazards which must have concentrations within a certain range rather than zero, such as conductivity or pH.

h) Update Storage risks:

1. Ensure that service reservoirs and other assets with diesel stores and generators on site are suitably assessed for the risk of diesel spillage or leaks and that appropriate control measures are documented as part of this process.
2. Review frequency of reservoir check visits and what is checked at these visits to ensure that animal activity can be detected and resolved, and therefore the company can ensure that control measures are working as expected.
3. Review microbiological parameters submitted under grouped and individual codes for the same risk.

i) Update Distribution risks:

1. Include the risk of providing ships with water within the company risk assessment.
2. Conduct a thorough risk assessment of vinyl chloride and include the details within the methodology, where appropriate.
3. Include Water Fittings inspections information within the Distribution and/or Consumer stage risk assessment.

j) Update Consumer risks:

1. Include risks from private supplies within the risk assessments.
2. Include the risk from back feeding in the risk assessments.

k) Update Bulk Supply risks:

1. Define the Bulk Supply stage within the methodology document, to include the naming and stage classification of bulk supply assets.
2. Update scoring mechanisms so the scoring is not generic.
3. Explain how the bulk supply protocol acts as a control measure within the methodology document.

Date by which requirement must be satisfied: 21 October 2027

2. Carry out updates to risks by site:
   a) Ensure all Water Treatment Works Operating Manual process site schematics are up to date.
   b) Review filter operation checks at sites where backwashing checks are undertaken to ensure that issues are identified and resolved in a timely manner  
   c) Ensure chemicals required for monitors have clearly labelled expiry dates and that there is a procedure to check these at a suitable frequency.
   Date by which requirement must be satisfied: 21 October 2027 
3. Produce a single overarching methodology document incorporating all requirements of this notice and demonstrating that all aspects of the WHO water safety planning approach have been included within DWSPs. The document should provide sufficient detail to enable interpretation of a company’s regulation 28 reports by parties not involved with the company DWSPs on a day-to-day basis.  
   Date by which requirement must be satisfied: 21 October 2027
4. Carry out updates to the training for drinking water safety planning teams: 
   a) Develop a specific training programme for drinking water safety plans, including a suitable sign off process where staff have been witnessed completing drinking water safety planning activities/processes.  
   b) Update roles and responsibilities to define the procedure and responsibility for adding hazards and hazardous events to standard lists and individual assets.
   Date by which requirement must be satisfied: 21 October 2027 

(c) Reporting:

1. Submit the revised or new risk assessment, methodology (as appropriate) and training as outlined in section 1 – 4, accompanied by a Board level Director sign-off.
   Date by which requirement must be satisfied: As soon as reasonably practicable upon completion. It is anticipated this would be by 21 October 2027

Signed

 

Nicholas Adjei

Deputy Chief Inspector, on behalf of the Welsh Ministers

3 October 2025

Reference: DWR-2024-00004