London’s £5bn Thames Tideway Tunnel is now fully connected, completing a decade-long construction project designed to protect the River Thames from sewage pollution.
The final link was made to the capital’s Victorian sewer network, completing all 21 connections. The 16-mile (25km) tunnel will divert flows from 34 of the most polluting sewage outfalls, which currently discharge into the river when the combined system is overwhelmed by rain and wastewater.
A major step, but testing is still to come
Tideway, the company behind the project, says the super sewer has already prevented around half a million tonnes of sewage entering the Thames. Once fully operational, it is expected to stop 95% of the spills that previously polluted the river.
The tunnel links with the existing 4.2-mile (6.9km) Lee Tunnel, creating the wider London Tideway Tunnel system. Connections were made at places including Putney Embankment, Chelsea and Victoria Embankments, Blackfriars Bridge and King Edward Memorial Park in Wapping.
The system still needs to be tested during storm conditions over the coming months before Thames Water takes over its operation. The project is also expected to support improvements in biodiversity, recreation and public health along the Thames.
Why it matters for Britain
The tunnel should make London’s river cleaner and reduce the impact of sewage discharges on wildlife, recreation and public health. It also offers a working example of large-scale infrastructure being used to tackle pollution in an ageing urban sewer network.
