The environmental performance of water companies fell again last year despite industry investment, according to the first joint report by the regulators.
Eight of the nine companies in England were rated as “poor” or “requiring improvement”, with only Severn Trent receiving the highest rating.
Companies were praised for reducing service disruptions but serious pollution into the environment remained a “major concern”.
The chair of the environmental regulator, Alan Lovell, said the results showed the industry continued to “fall well short of the standards rightly demanded by both us and the public”.
“I’m very angry,” he told BBC News. “I think it’s extremely disappointing to see the level of pollution incidents… and I completely sympathise with the public.”
Environment Secretary Dame Angela Eagle said she was “demanding answers from the companies that are failing” and would be “shining a spotlight on the worst offences around the country”.
Four different regulators currently oversee water companies in England and Wales – the Environment Agency (EA), Natural Resources Wales, Ofwat and the Drinking Water Inspectorate – and this marks the first time they have come together to assess the industry.
It is a nod to the commitment which Sir Keir Starmer’s government made to merge the organisations covering England into a single body as part of efforts to streamline regulation.
The Welsh government plans to set up a new regulator alongside Natural Resources Wales.
But it is on environmental performance that the report is most critical.
Serious pollution incidents in 2025 were a “major concern”, the Environment Agency said, and remained at similarly high levels to those seen in previous years.
Overall, England’s water companies were awarded 16 out of a possible 36 stars for environmental performance – the worst total on record.
The EA said this was due to “declining performance in some areas but also due to our tighter performance standards”.
And in Wales, Dŵr Cymru Welsh Water was given a two-star rating, out of four, by Natural Resources Wales.
Industry body Water UK acknowledged that “the environmental performance of some water companies is not good enough”.
But it also pointed out that more than half of all pollution incidents were as a result of “blockages or vandalism, which are not in the direct control of the water companies”.
“It will take time, but record investment will help secure water supplies, support growth, and end sewage entering rivers and seas,” a spokesperson said.