Water firms’ environmental performance sinks as serious pollution cases up 60%

England’s embattled water companies have chalked up their lowest environmental performance ratings on record, with serious pollution incidents up 60% last year.

The Environment Agency called for a fundamental shift in culture and behaviour from English water firms in the light of “poor” results across the sector.

The regulator, which rates water firms annually on a one to four star basis, said only Severn Trent scored the top four-star rating on its performance in areas including pollution, sewage and improving the environment.

Overall, the nine companies collectively achieved just 19 stars out of a possible 36 in 2024, down from the 25 in 2023 and the lowest since the process started in 2011.

Beleaguered Thames Water, which is beset by financial problems, was alone in scoring the worst rating of just one star, as it saw serious pollution incidents more than double to 33 cases last year.

The rest of the companies only managed two stars, the report showed.

The Environment Agency (EA) said the criteria for the annual environmental performance assessment has tightened over time and the trend since 2011 has been one of improvement, but that came to an end in 2024.

Serious pollution incidents which caused significant environmental harm increased by 60% between 2023 and 2024 to 75 cases, the assessment shows, and were at their highest since the peak years of 2013 and 2011.

Thames Water, Southern Water and Yorkshire Water were responsible for more than four-fifths (81%) of the serious incidents, while Northumbrian Water and Wessex Water recorded none.

The EA said the decline was down in part to the fact 2024 was a very wet and stormy year, which put extra pressure on water company assets – though it warned “this is never an excuse”.

The regulator also pointed the finger at long term underinvestment and poor maintenance, and said greater monitoring is bringing more failings to light.

Environment Agency chairman Alan Lovell said: “This year’s results are poor and must serve as a clear and urgent signal for change.

“What is needed now from every water company is bold leadership, a shift in mindset, and a relentless focus on delivery.

“We will support them however we can but will continue to robustly challenge them when they fall short.”

In light of the findings, Environment Secretary Emma Reynolds said: “We are facing a water system failure that has left our infrastructure crumbling and sewage spilling into our rivers.

“Under this Government, water company inspections and criminal investigations have reached record levels, uncovering the true extent of the problem. We are taking decisive action to fix it, including new powers to ban unfair bonuses, and swift financial penalties for environmental offences.”

She also said there would be £104 billion in private investment for infrastructure upgrades and a new, single water regulator.

A second report from Ofwat on water company performance across a number of areas found a mixed picture for 2024/25, with almost all companies improving areas such as internal sewer flooding incidents, leakage rates, the health of their assets and water supply interruptions.

But almost all had overspent on water and wastewater, while pollution incidents were at an “unacceptable level” and customer satisfaction had fallen to its lowest level since the measure was introduced, the regulator said.

The latest reports come against a backdrop of widespread public anger over the state of England’s water system, with widely polluted and degraded rivers, lakes and coasts, soaring bills, executive bonuses and shareholder payouts.

River Action chief executive James Wallace said: “Today’s report shows that water companies in England and Wales are still underperforming, especially on serious pollution incidents, exposing the bankruptcy of the privatised water model.

“We urgently need a complete overhaul of this failed system to ensure that bill payers receive a fair service and that our rivers are properly protected from pollution.”

Giles Bristow, chief executive at Surfers Against Sewage, said water companies “fail, fail and fail again” as he called for the industry to be put into special administration.

“This system is broken and speaks only one language: money,” he said.

“Until that changes, and until public health and the environment come first, the sewage scandal will never end.”

A Thames Water spokesperson said the company made a record capital investment in 2024/25 of £2.225 billion.

“We know we need to further improve for our customers, communities and the environment, and that is why we have embarked on the largest ever investment programme, delivering the biggest upgrade to our network in 150 years,” they said.

“Transforming Thames is a major programme of work that will take time; it will take at least a decade to achieve the scale of change required.”

A spokesperson for industry body Water UK said: “While there are some areas of good performance, like the lowest leakage on record, the performance of some companies is not good enough.

“After over a decade of suppressing investment, Ofwat has finally allowed companies to invest £104 billion over the next five years.

“It will take time, but we are confident this record investment will help to secure our water supplies, support economic growth and end sewage entering our rivers and seas.”