London’s super sewer promises a cleaner Thames

A 24m-wide concrete lid was lifted over the shaft at Abbey Mills Pumping Station. Image: Thames Tideway Tunnel

Underground construction of London’s 25km-long super sewer is complete.

Known as the Thames Tideway Tunnel, the 7.2m-wide stormwater sewer has been built to dramatically reduce pollution in the central London River Thames.

The final piece of the puzzle - a 1,200-tonne concrete lid - was lifted on top of a 70m-deep shaft at Abbey Mills Pumping Station in Stratford, East London, in March 2024. Testing and commissioning will follow, with full operation planned for 2025.

"This marks an absolutely critical milestone for the Tideway project and for London.”

Andy Mitchell, Tideway

In a typical year, tens of millions of tonnes of storm sewage spill into the River Thames. Once fully operational, the super sewer will reduce those spills almost completely, says Tideway, the company behind it.

Once operational, the super sewer will reduce sewage spills. Image: Thames Tideway Tunnel

Tideway chief executive Andy Mitchell said: “This is the moment we’ve all been waiting for. The underground civil engineering on the Tideway project is now complete following eight years of dedicated hard work from all our teams working in the capital.

“There is still work to do – we need to finish some above-ground structures and, crucially, test the system – but this nonetheless marks an absolutely critical milestone for the Tideway project and for London.”

As well as the main tunnel, the project’s infrastructure includes 4.5km connection tunnel in south-east London, and a 1.1km tunnel in south-west London.

Victoria Embankment will be one of seven public spaces created. Image: Thames Tideway Tunnel

Next, Tideway looks ahead to the start of commissioning. This will likely begin over the summer, when live storm sewage flows will be diverted into the new infrastructure – essentially protecting the River Thames for the first time.

Tideway is also continuing architecture and landscaping works at seven sites along the route of the tunnel, including Blackfriars, Victoria and Chelsea. These sites will eventually be accessible to the public, offering a new vantage point of the city.