The Thames Tideway Tunnel project has intercepted more than 18 million tonnes of sewage in the first year since London’s super sewer began offering full protection of the River Thames.

While the tunnel is designed to protect the river for decades and centuries to come, marking the first 12 months is a significant milestone on the road to a greener, healthier future for the Thames.

When the final connection was made on Valentine’s Day, 202,  Tideway launched an online ‘tracker’ showing the volume of sewage captured by the tunnel – flows that would historically have spilled directly into the river, untreated. Figures published one year on showed the number standing at 18.4 million – with the number continuing to climb.

Jad Bhudia, system commissioning manager, said: “Capturing more than 18 million tonnes of sewage in the first year is a powerful demonstration of what this new system is already delivering for the River Thames. This is an important milestone – but it’s only the beginning.

“As the tunnel continues to operate, we expect to see the river respond and improve over time, with lasting benefits for wildlife, river users and London for generations to come.”

The staggering volume of sewage already kept out of the Thames – equivalent to filling Wembley Stadium four-and-a-half times over – comes despite long periods of unusually dry weather during 2025, underlining the scale of pollution the tunnel is designed to prevent.

And, while the last 12 months has seen the tunnel operating underground, there have been many key milestones above ground, too – transforming former construction sites into new public spaces and cultural destinations along the river.

Public spaces built atop the vital infrastructure below were opened in Fulham, Vauxhall, Nine Elms, Westminster, Deptford and in the City of London. Elsewhere, beautiful public artworks were unveiled in Greenwich, Surrey Quays and many other sites.

The £4.5bn, 25km-long ‘super sewer’ that runs beneath London took eight years to construct. Around 25,000 individuals worked on the project – including tunnellers, engineers and divers – contributing 40 million work hours.

Experts involved in this innovative infrastructure project, which will protect the Thames for at least the next 120 years, will be sharing their insight at the ACE/EIC Delivering Infrastructure 2050 conference, being held in London on 30 June.

Roger Bailey, chief technical officer at Tideway – the consortium of contractors who built the £4.5bn tunnel – will be among the line-up of speakers at the event.

An engineer, he has been part of the project since 2012 and has been instrumental in defining the project requirements and agreeing the technical interaction between Tideway and the existing Thames Water sewer network.

For more details on the Delivering Infrastructure 2050 conference, and to book your place, click here