Mayor of London blasts the state of its rivers as election nears

Mayor of London, Sadiq Khan, has brought the state of the capital’s rivers into his election campaign, last week lambasting both Thames Water and ministers and telling them to get a grip of the situation.

Analysis of Thames’ published data released by the City Hall set out that between April and December 2023, Thames Water released sewage into London's waterways for 6,590 hours, 11 minutes and 54 seconds – a five-fold increase on the same period the previous year. City Hall highlighted especially that between 25 December and 31 December 2023, sewage was released across the Thames network for 128 hours and 12 minutes, equivalent to 18 hours every day.

However, the discharge data included both treated sewage and overflows of untreated sewage and storm water into rivers, skewing the picture given treated effluent is designed to be released back to the environment. Nor was there any mention of the Tideway Tunnel development or the different weather conditions in 2022 or 2023, which would partially explain the performance change across the two years.

In a letter to new Thames Water chief executive, Chris Weston, the mayor highlighted the scale of the challenge, arguing that decades of under investment has led to London now having no healthy rivers. He gave the example of the River Wandle which was the last London river to lose its “good” status in summer of 2023 – and which, Khan said, is now set to have sewage spills continuing until at least 2035.

The mayor urged Weston to urgently get to grips with the problems. He also called on ministers to do more to get a “grip of the crisis”. Specifically to:

• “develop a plan to guide Thames Water back to strong financial health in a way which doesn’t delaying the cleaning up of London’s rivers;

• deliver the essential water network upgrades that are needed, while protecting Londoners from increased bills; and

• introduce tougher legislation that forces water companies to end sewage discharge into rivers. This should include tougher penalties for water companies.”

Khan said: “While we’re making huge progress cleaning up London’s air and much of the capital’s environment, it’s a scandal that levels of sewage in our rivers are increasing at the same time.”

A Thames Water spokesperson said: “We regard all discharges as unacceptable and are committed to reducing the need for them. The Thames Tideway Tunnel, a £4.5bn investment, is nearing completion. This project, combined with previous upgrades we’ve made to our London sewage works and the building of the Lee Tunnel, will capture 95% of the volume of untreated sewage currently entering the tidal Thames in a typical year.”

The spokesperson also highlighted that Thames remains the only company to provide live alerts for all untreated discharges in near real time online, and that it has published plans to upgrade over 250 sewage works to stem spills.

The London mayoral election is set to take place in May.