Data shows mixed picture for water company environmental performance

Nation Cymru staff

Natural Resources Wales (NRW) has published its 2025 annual environmental performance reports and storm overflow spill data for Dŵr Cymru Welsh Water and Hafren Dyfrdwy, with concerns raised amid the highest number of serious pollution incidents on record.

The results show progress alongside ongoing challenges. Hafren Dyfrdwy continues to perform strongly in several areas, while Dŵr Cymru Welsh Water has shown improvements in some measures but remains a company requiring improvement in line with the Environmental Performance Assessment (EPA).

Although Dŵr Cymru Welsh Water’s pollution incidents from wastewater assets fell from 132 in 2024 to 107 in 2025, serious pollution incidents increased from 6 to 9 in the same period.

The number of serious pollution incidents is the highest recorded under the current assessment framework and a significant cause for concern. Every serious incident, by definition, causes environmental damage. The continued occurrence of these incidents highlights the need for action to reduce the harm they cause.

The company improved storm overflow monitoring, reduced some pollution indicators and increased self-reporting of incidents. However, reporting rates remain below expectations and concerns remain around permit compliance, wastewater treatment compliance and the pace of environmental improvement.

Dŵr Cymru Welsh Water is Wales’ largest provider of drinking water and wastewater services, while Hafren Dyfrdwy, part of the Severn Trent group, provides services to parts of north and mid Wales.

Hafren Dyfrdwy does not receive an EPA star rating because of its smaller size, but NRW still publishes an assessment of its environmental performance.

In 2025, the company performed well in several key areas, with no serious pollution incidents and an excellent level of compliance with wastewater discharge permits for the third year in a row.

It also recorded just 3 incidents overall, down from 5 in 2024 and the lowest number since 2015. One incident was not self-reported.

Storm overflow spill data for 2025 shows both water companies recorded fewer spills than in the previous year, alongside improved reliability of monitoring equipment. However, frequent spilling remains a significant concern. Across Wales, almost a third of monitored overflows spilled between 40 and 99 times during 2025, while more than one in 10 spilled over 100 times.

Nadia De Longhi, NRW’s Head of Regulation said: “These results show some encouraging signs of progress, but the overall picture remains mixed.

“Hafren Dyfrdwy continues to perform strongly, with year-on-year improvements in several areas. It is also positive to see improvements in some aspects of Dŵr Cymru Welsh Water’s performance, including fewer pollution incidents and better storm overflow monitoring.

“However, serious pollution incidents remain a significant concern. Every serious pollution incident causes environmental harm, and reducing these incidents must remain a priority.

“Stronger regulation, increased monitoring and significant investment are helping to drive improvements, but it will take time for these changes to deliver the level of environmental improvement that people rightly expect to see across Wales.”

Marcus Rink, Chief Inspector of the Drinking Water Inspectorate said:  “Consumers in England and Wales can have continued confidence that their drinking water remains among the highest quality in the world, with 99.97% of tests meeting the strict standards that protect public health. That is a record the industry should be proud of.

“This report marks a significant first step, bringing four regulators together for the first time to give a more transparent and collaborative picture of the water sector. It is a foundation we intend to build on, working ever more closely to ensure clean and resilient drinking water supply now and for the future”

Philip Duffy, Chief Executive at the Environment Agency, said: “People expect two simple things: safe water from their taps and clean, healthy rivers. Today’s report shows good performance on drinking water quality, but on wastewater and pollution the sector is still falling short.

“We are stepping up inspections and enforcement and will use our powers to hold water companies to account and drive the improvements people and the environment deserve.”

Helen Campbell, Interim Executive Director for Delivery at Ofwat, said: “Customers rightly expect the record investment approved by Ofwat to deliver tangible improvements in their daily lives and for the environment.

“Over the past year we have seen some step up to this challenge, but this is inconsistent and poor performance continues in too many places.

“The responsibility sits with water companies to deliver on what they have agreed to, and we will continue to work across regulators to drive stronger outcomes.”

Ceri Davies, Chief Executive of Natural Resources Wales, said: “Improving water quality is one of the most significant environmental challenges we face. This joint insights report provides a clearer picture of water company performance by bringing together evidence from across the regulatory systems.

“While progress has been made in some areas, there is more to do. We will continue to work with partners across the sector to drive improvements that benefit people, nature and the resilience of our water environment.”

Today’s figures reflect greater scrutiny as much as they do underlying performance. Where performance falls short, regulators will act, using the full range of tools available, including fines, enforcement action and requirements for companies to fix problems. Regulators will support companies where they are improving and continue to challenge them where standards aren’t met.

Water companies have committed record levels of investment for 2025 to 2030, with over £104 billion to upgrade water and sewage networks. Regulators are committed to ensuring this investment is well spent and delivers for customers, communities and the environment.

A Welsh Water spokesperson said: “We recognise that our environmental performance is not good enough. Our customers and communities rightly expect better, and we apologise for the environmental harm we have caused.

“We have worked hard in 2025 but much remains to be done. There were signs of progress though: we improved against two of the six Environmental Performance Assessment measures and recorded the second-lowest rate of pollution incidents per 10,000 kilometres of sewer in the sector.

“We also improved against several Ofwat performance measures, with fewer customer contacts about water quality, less internal sewer flooding and shorter water supply interruptions.

“These improvements are important, but not sufficient and we must build on them and deliver consistently better results across all areas of our service.

“We are tackling the causes of pollution and improving our operations. We are delivering the investment needed for lasting improvement. Between 2025 and 2030, we are investing £4.2 billion in our infrastructure, including £2.5 billion on environmental improvements to reduce pollution and improve river and coastal water quality.

“This investment is supported by a fundamental transformation programme started in 2026, including a new leadership team, a full organisational restructure and a new operating model. These changes are reshaping how we work across the company, strengthening operational oversight and making accountability for performance and customer service clearer.

“From 2026, changes to regulatory reporting guidance mean a wider range of discharges will be counted as pollution incidents, including some previously not counted because they have no environmental impact. Natural Resources Wales expects this to increase reported numbers across the industry even if the performance doesn’t change, so future totals will need to be understood in that context when comparing performance with earlier years. Our commitment to prevent pollution and reduce environmental harm remains unchanged.

“We know that rebuilding trust depends on results. Our focus is on ensuring that our investment and the changes we are making deliver sustained, measurable improvements for our customers and the environment.”

The full reports are available on the NRW website:

Annual performance report for Dwr Cymru Welsh Water

Annual performance reports for Hafren Dyfrdwy

Storm overflow spill data reports

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