Thames Water must “get a grip” on river pollution, Sadiq Khan has said, after an analysis revealed the duration of sewage spills in London increased more than fourfold last year.

Adam Vaughan www.thetimes.co.uk /

“Frankly the current state of some of our rivers is appalling and only getting worse. Thames Water urgently need to up their game, and get a grip of the situation,” said the mayor of London.

Khan has invested considerable political capital in tackling air pollution, resisting pressure last summer for a U-turn on expanding the ultra low emissions zone. But this is the first time he has turned his focus on water pollution.

Data from Thames Water, analysed by City Hall, shows there were 6,590 hours of sewage spills in the last nine months of 2023, up from 1,420 hours for the same period in 2022. The figures only started being published in April 2022, preventing a full year comparison.

Between 25 and 31 December last year, sewage was dumped 18 hours a day on average, amid heavy rainfall.

Khan has written to Chris Weston, who was appointed chief executive of Thames Water last month, calling for more action. In the letter, he expressed his dismay at slow action on sewage spills into the River Wandle. Last year the river became the last in London to be downgraded from “good” ecological status, meaning close to its natural state, to “moderate”.

“I have many fond memories of walking alongside the Wandle with my family. As one of our few treasured chalk stream rivers, it is a truly precious asset, and I am deeply disappointed on behalf of Londoners that you have inherited an approach that is not prioritising its restoration,” Khan told Weston.

Storm overflows, which act as emergency valves on the sewer network, are designed to spill sewage into waterways during times of heavy rainfall. While 2022 was dry with a months-long drought in many parts of the country, 2023 was much wetter — July was the sixth wettest on record.

Thames Water, which has built a £4.5 billion “supersewer” under London that is expected to begin trial operations at the end of this year, noted it was still the only water firm to offer a real-time map of sewage spills into rivers. A spokesman said: “Taking action to improve the health of our rivers is a key focus for us and we are leading the way with our transparent approach to data.”

Khan also accused the government, which has a plan of effectively ending spills by 2050, of not doing enough to stop discharges of raw sewage. “Ministers are standing by and letting more and more dirty sewage flow into our rivers. We need tougher legislation that forces water companies to act as a matter of urgency,” he said.

However, the chief executives of ­England’s water companies were pressured this week over their record by Steve Barclay, the new environment secretary. At a meeting yesterday, he is understood to have told bosses he was “shocked and appalled” at what appears to be routine law-breaking due to pollution incidents in the water industry.

People in the room said Barclay made it clear that bonuses should not be paid to leaders of any companies where such illegality takes place. The Labour party this week reiterated its plan to ban bonuses at polluting firms, finding water bosses had taken £26 million in bonuses since the last election.

Meanwhile, England’s post-Brexit environment watchdog said the government may have broken the law through inaction on stopping farmers from polluting rivers.

In a ruling on a complaint by green groups ClientEarth and WWF, the Office for Environmental Protection said: “We believe Defra may have failed to comply with environmental law and, if it has, we consider that failure would be serious.” The complaint hinged on whether the Department for Environment, Food and Rural Affairs was sending enough inspectors to farms to check for breaches of water pollution rules.

A river in Lyme Regis is now closely monitored after tourists complained of a bad smell

“The government must [now] revise their guidelines and we hope this will help bring river pollution under control as soon as possible,” said Kyle Lischak, head of UK at ClientEarth, an environmental law charity.

A Defra spokesperson said: “We have set highly ambitious legally binding targets to reduce water pollution from agriculture, and just last year more than 4,000 farm inspections were carried out to ensure farmers comply with legal requirements.”