9 July: Drinking Water Inspectorate – Chief Inspector’s Annual Report 2025 Wales
The Drinking Water Inspectorate (the Inspectorate) today publishes the Chief Inspector’s Annual Report for Wales, covering the quality of public drinking water supplies during 2025. The report sets out a comprehensive picture of drinking water quality across Wales, drawing on compliance data, events, audits and emerging risks.
Marcus Rink, Chief Inspector of Drinking Water said:
“Consumers in England and Wales should have continued confidence that their drinking water is amongst the highest quality in the world. This year’s report shows that 99.97% of regulatory samples collected from public water supplies met the stringent standards in place to protect public health.”
“While drinking water quality remains high, the industry faces significant long-term challenges. This report highlights concerns regarding asset health, particularly of tanks and service reservoirs. Additionally, ensuring sufficient and resilient water supplies is becoming an increasingly pressing issue and one of public concern due to its widespread impacts to communities and the economy. Addressing these challenges will require sustained investment, innovation and effective regulation.”
“This report demonstrates the repercussions to companies when they fail in their duties to supply wholesome drinking water to consumers. As the government takes forward wider reforms through the Clean Water Bill and plans for a single water regulator, it is vital that focus remains on protecting public health and maintaining the high standards that consumers rightly expect. The Inspectorate will continue to provide independent evidence-based oversight to help secure safe, resilient and reliable drinking water now and for future generations.”
Key headlines from the 2025 report:
- Compliance: Public water supplies in Wales complied with regulatory standards in 99.97% of tests in 2025, across over 260,000 water quality compliance tests. Of the 91 failures, 32 were related to consumer’s own distribution systems. Compliance failures in Wales included: 33 coliform bacteria failures at consumer taps, 21 coliform bacteria failures elsewhere, 18 iron failures, 5 odour failures, 5 taste failures, 4 E. coli failures, 2 lead failures, and 1 each for turbidity, manganese, and turbidity at treatment works. The Compliance Risk Index (CRI) which measures the risk to consumers from non-compliance, shows a total CRI score for Wales as 6.732, a deterioration from last year’s score of 4.08.
- Events: 65 water quality events were reported to the Inspectorate in 2025, with 0 major events, 1 serious event, 45 minor events and 14 not significant events. 25 of these reported events (38%) occurred on consumer premises and were attributed to the consumers’ distribution system. The Inspectorate uses the Event Risk Index (ERI) which measures the impact of events on consumers, and in 2025 the combined ERI score for Wales was 5,370.
- Audits: The Inspectorate completed 10 audits across Wales in 2025 with 24 recommendations made to water companies. Recurring themes included the condition and management of air valves, the adequacy of bottled water storage facilities, and the robustness of data management systems. Findings reinforce that effective asset oversight and data governance are fundamental to protecting drinking water quality.
- PFAS: PFAS remain a significant focus for the Inspectorate in Wales. In 2025, companies in Wales carried out 30,000 analyses for individual PFAS, bringing the total since 2012 to more than 2.3 million analyses for both England and Wales. Perfluoro-butanoic acid (PFBA) was the most detected single parameter in 2025. Companies have now implemented reporting for the ‘sum of PFAS’ based on the calculation of the results of analysis from all 48 named PFAS. There were no PFAS detections in treated waters in Wales at or above the Inspectorate’s guidance value of 0.1 ug/L in 2025.
- Lead: There were 2 compliance sample failures for lead in 2025 from 747 samples analysed, both with a concentration reported of 11 µg/L. The primary source of lead in drinking water remains lead pipes and internal plumbing. Both failures were attributed to the domestic plumbing. Water companies have collectively declared an ambition to be lead pipe free by 2050, and the Inspectorate continues to work with industry and government to drive progress toward that goal.
- Asset Health: Asset condition and the integrity of treated water storage remain key risks in Wales. There are 815 service reservoirs in Wales with 8 of them not being inspected in 10 years. There were 3 water quality events attributed directly to poor asset health, including 2 microbiological contamination events at reservoirs and 1 microbiological contamination event at a treatment works. Air valves remain a key asset at risk and the Inspectorate undertook an industry wide programme of technical audits focused on the management of air valves across water companies with 8 recommendations made in Wales and 18,273 air valves in unknown condition.
- Consumer Contacts: In 2025, 9,195 consumer contacts were received in Wales relating to the appearance, taste or odour of drinking water. Of these, 5,149 were for discolouration, producing a contact rate of 2.46 per 1,000 consumers. The discolouration contact rate performance has remained flat, with no meaningful improvement in recent years. This is of concern to the Inspectorate: discolouration directly affects consumer confidence in the safety of their supply and must be addressed through sustained investment in network management and asset condition.
- Enforcement: The Inspectorate holds a range of enforcement powers to compel companies to deliver drinking water of the highest quality and to ensure the resilience of the systems that supply it. In 2025, 3 notices were served in Wales and one company – Dŵr Cymru (Welsh Water) – is currently subject to a transformation programme. The Inspectorate will continue to use its full range of enforcement tools to ensure that Welsh consumers receive the safe, reliable drinking water they are entitled to expect.