It has been one year since London’s super sewer began offering its full protection of the River Thames – with more than 18 million tonnes of sewage intercepted by the vital new infrastructure.

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, 2025) 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.

Since then, the tracker has gradually ticked upward. Today it stands at around 18.4 million.

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.

And as the numbers continue to rise, the tracker will offer a visible reminder of the difference this new infrastructure is making to the health of the River Thames.