River Thames: Sadiq Khan plans to make London's famously polluted river 'so clean people can swim in it'

Sadiq Khan has branded the sewage-tainted Thames a “national embarrassment”, and vowed to clean it up so that it’s safe enough to swim in within a decade.

Over the weekend, the Mayor told The Sunday Times about his new, “moonshot” plan to clean up the iconic London waterway, in the form of an ambitious ten-year plan. The River Thames has been plagued by an ongoing pollution problem dating back to the 1800s, and the Royal Museums say it and its tributaries have long been the final resting place for all manner of domestic and industrial waste.

More recently, it’s hit the headlines as part of a broader sewage spill scandal across the UK. In January, figures released by water firm Thames Water and fact-checked by City Hall showed that the amount of raw sewage dumped in the Thames quadrupled last year, with 6,590 hours of sewage spills recorded in the last nine months of 2023 - up from 1,420 hours for the same period in 2022. Last year was notably wetter than its predecessor, however, with heavy rainfall overwhelming leaky pipes and older sewerage systems a key contributor.

Last year, an Environment Agency report also found that Thames Water had the highest number of serious sewage spill incidents in a decade in 2022 at 17, which it criticised the decline as “simply unacceptable”. On Monday (22 April), Thames Water - which serves 15 million customers across London and southeast England - put forward new plans to boost investment in its network, but warned this could see customer bills surge by up to 44%.

Khan told the Times that under his leadership, the capital had “made huge progress” cleaning up its air. This in part came in the form of Greater London’s ULEZ expansion last year, which has been highly contentious in some circles due to the cost for people and businesses in outer London suburbs - although grants for replacing vehicles were available. However, official data released by London City Hall suggested that the original ULEZ policy had been highly effective, cutting harmful nitrogen dioxide levels along roads by 21% in Inner London and 46% in Central London since it was first introduced in April 2019.

“Now it’s time to clean up our waterways too and build a plan to make rivers in London swimmable again within ten years,” the Mayor continued. “The levels of sewage that water companies are pouring into our rivers is a scandal. Thames Water urgently need to up its game and get a grip of the situation.”

In his role as mayor, Labour-aligned Khan said he did not have the power to turn around the river’s decline alone - although he praised tough policy making, like the Labour Party’s vow to ban CEOs of sewage polluting water companies from getting bonuses. “It just needs political will, and determination across the political spectrum to deliver real change. I will commit to bringing together the companies, government agencies and campaigners to work together on a ten-year plan to get London’s rivers so clean they are safe to swim in,” he continued.

NationalWorld has approached Thames Water for comment.

Across the Channel, Paris has committed to making the once-polluted Seine safe to swim in - part of its 2016 bid for the 2024 Olympic Games. The city has since poured more than €1.4 billion (£1.2 billion) into solving the iconic waterway’s pollution problem, so that open-water swimming races could safely be held there.

The French capital has made a long-term commitment too, with plans for swimming spots for residents and tourists alike which will remain long after the games have ended. City Hall last year said that the Seine's water quality had been improving since work began, and more species of fish had appeared - drawing comparisons from British environmentalists to the Thames’ ongoing sewage spill problem.