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Thames super sewer cuts sewage overflows, company report says
Thames Water reports an 86% reduction in raw sewage entering the tidal Thames in 2025. Pollution and climate pressures remain.
By NewsCubby · Published
London’s new super sewer sharply reduced raw sewage entering the tidal River Thames in its first year of full operation, according to a Thames Water report covered by BBC News on October 12.
The company reported an 86% reduction in 2025 compared with the previous average. It also estimated that the system prevented about 84 tonnes of litter, including wet wipes, from reaching the river. These are the company’s reported results, rather than a declaration that the Thames is free of pollution.
The Thames Tideway Tunnel gives London’s sewer system additional capacity during heavy rain. Instead of allowing as much mixed rainwater and sewage to overflow into the river, the system stores and transfers it for treatment. The 16-mile tunnel runs from Acton in west London to Abbey Mills in the east, with wastewater sent onward to Beckton for treatment.
The £5 billion project took eight years to build and entered full use in 2025. Thames Water says pollution and climate change remain major challenges. River charity Thames21 welcomed the engineering achievement while stressing the importance of nature-based measures to manage increasingly extreme rainfall.
The practical takeaway: the report points to substantial progress in controlling sewage overflows, but it does not establish that the river is safe for swimming.
Reporting: Aurelia Foster, BBC News; Thames Water’s 2025 benefits realisation report.
Social image: London and River Thames, March 25, 2024, John Dillenbeck / CC0. File photograph; cropped with AI-assisted headline layout.