The Thames Tideway Tunnel is set to bring environmental benefits worth up to almost £13 billion, Environment Minister Rory Stewart has announced.
The Minister was commenting on two new papers released by the Department for Environment Food and Rural Affairs setting out an updated strategic and economic case for the Thames Tideway Tunnel, together with a costs and benefits update.
Defra has separately also published a final report on the economic valuation of the Thames Tideway Tunnel environmental benefits.
Work on the tunnel is set to begin next summer and will update the capital’s 150-year-old sewerage system now operating close to capacity, resulting in sewage overflowing into the river on average once a week.
Environment Minister Rory Stewart said:
“London is one of the most dynamic cities in the world and it is vital we have a river that is not filled with sewage every time there is heavy rainfall.”
“This new research reveals the tunnel will bring up to £13bn worth of benefits to the capital’s natural environment. It will prevent millions of tonnes of sewage flowing into the river every year and it will mean we will have cleaner water for all to enjoy and improved water quality to better protect the Thames’ precious marine wildlife.”
The Minister announced the new figures on a visit to the Lee Tunnel at Abbey Mills Pumping Station. Spanning four miles beneath the London Borough of Newham, from Abbey Mills to Beckton, the Lee Tunnel is London’s deepest-ever tunnel and will prevent more than 16 million tonnes of sewage mixed with rainwater overflowing into the River Lee and Thames Tideway each year.
Martin Baggs, Chief Executive Officer, Thames Water, said:
“Our programme of London Tideway improvements including updating our sewage works, building the Lee Tunnel and then the Thames Tideway Tunnel will help make London’s sewerage system fit for the 21st Century. Beyond delivering the benefits of a cleaner river, a healthier environment and allowing us to harness more renewable energy from wastewater, this programme of investment will help many thousands of people forge a career in improving our Capital’s infrastructure.”
Click here to download Creating a River Thames fit for our future - An updated strategic and economic case for the Thames Tideway Tunnel
Click here to download Costs and benefits of the Thames Tideway Tunnel 2015 update
Click here to download Update of the Economic Valuation of Thames Tideway Tunnel Environmental Benefits - Final Report
With the UK government demanding a 50% reduction in storm overflow spills by 2029, the era of reactive management is over. Speaking in the House of Commons on 21 July 2025, then environment secretary Steve Reed said, “This Government will cut water companies’ sewage pollution in half by the end of the decade.”
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