The London capital is stepping up protection for its river with the full activation of the Thames Tideway Tunnel , a deep drainage system designed to reduce wastewater discharges into the Thames by 95%. Tideway has confirmed that all 21 connections between the new super sewer and the Victorian infrastructure are complete and operational.
Improving urban sanitation with the Thames Tideway Tunnel
London’s sewer system , built in the 19th century, was designed for four million people but now serves more than nine million. Heavy rainfall overloaded the network, leading to sewage overflows into the Thames. With the new, fully integrated system, the city is dramatically reducing these spills and improving water quality .
Since connections began in 2024, the supersewer has captured 5.5 million m³ of wastewater, equivalent to 2,200 Olympic-sized swimming pools. Tideway has launched a data tracker on its website to monitor the amount of effluent retained in real time.
Tideway led the construction of the Thames Tideway Tunnel , a £4.5bn mega-project funded by Thames Water customers. Construction, which began in 2016, took place at 24 sites across London and required tunnelling up to 25km long and 66 metres deep.
These are the different engineering consortia that carried out the works in three regions: BAM Nuttall , Morgan Sindall Infrastructure and Balfour Beatty in the west; Ferrovial Agroman UK and Laing O’Rourke in the centre; and Costain , Vinci Construction Grands Projets and Bachy Soletanche in the east. Amey was responsible for the integration of the system, ensuring its operability.
Environmental benefits and the future of the Thames
With this infrastructure in place, a substantial improvement in the biodiversity of the Thames is expected, benefiting aquatic wildlife and reducing risks to public health. Steve Reed, UK Environment Secretary, said: ” This Government is determined to clean up our polluted rivers, lakes and seas, and that includes the capital’s iconic River Thames .”
This is a major milestone that will lead to a huge reduction in wastewater entering the River Thames. We must now build on this work to go further and tackle the other sources of pollution damaging London’s waterways.
Sadiq Khan, Mayor of London.
As environmental regulator and adviser, the Environment Agency is proud to have worked collaboratively with partners in delivering the Tideway project every step of the way, from conception to construction and the ongoing regulation of sewage spills into the Thames Estuary, which will be reduced by around 95% through the combined improvements to London Tideway.
Alan Lovell, Chairman of the Environment Agency.
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Source and photos: Tideway
