London’s 25-kilometer-long super sewer has been completed

The construction of the Thames Tideway Tunnel was completed on March 27, 2024, with the placement of a 1,200-ton concrete lid onto a shaft located in Stratford.

Furthermore, work on the project commenced in 2016 and lasted about 8 years, while it came at a total cost of £5 million, which was higher than the initial estimate of £4.2 billion.

The project’s cost is going to be paid for over the following decades by Thames Water, which is expected to increase water bills by up to £25 per year.

This is the biggest upgrade that London’s Victorian sewage network has seen since it was first built in the 1860s by Joseph Bazalgette.

As for the 7.2 m diameter super sewer’s alignment, it runs for 25 kilometers under the river Thames, reaching a maximum depth of 70 m, at its connection point with the Lee Tunnel. It is worth noting that the Lee Tunnel is a similar 6.9 km overflow sewer project, running in East London.

Thames Tideway Tunnel aims at almost eliminating the amount of the city’s unprocessed sewage waste that ends up in the Thames, by diverting 34 of the most polluting outflows currently discharging in it.

The waste can then be stored in the super sewer, which is capable of storing the equivalent of 600 Olympic sized swimming pools in it, to later be processed in the Beckton sewage treatment works, one of Europe’s largest treatment plants.

Finally, the project is scheduled to receive its first inflow during the summer and go into full operation in 2025.