The big clean-up of London’s sewage system is underway

London’s skyline is scattered with cranes building surface structures to house and serve its ever-growing population, but along the city’s river, an even more momentous construction is taking shape below ground.

This 25 kilometre tunnel running below the Thames from west to east is being delivered by Tideway, a company that prides itself on reconnecting London with its largest river and greatest natural asset.

The River Thames is in many ways the heart of London; it’s the reason the city was established in the first place, and for thousands of years it has been used as a source of food, as a transport artery, and for recreation and industry. Its historic importance cannot be overstated, and Tideway’s ambition is to not only improve the quality of the river water, but also the lives of the communities through which it runs.

The Thames Tideway Tunnel is a £4.1 billion sewer upgrade currently under construction deep beneath London. Its primary goal is to clean up the Thames, by intercepting millions of tonnes of raw sewage that currently pollute the river from the existing Victorian infrastructure and diverting them into the new tunnel.

The project represents the biggest upgrade to London’s sewerage system since it was first constructed by Sir Joseph Bazalgette, chief engineer of the Metropolitan Board of Works, in the 1860s, and is the largest project ever undertaken by the UK’s water industry. Overflows from Bazalgette’s system will be reduced by 95 per cent when the tunnel becomes operational in 2025, massively ameliorating the water quality and offering a range of benefits for the ecology, recreational river users and Londoners in general. 

Governed by a desire to showcase not only the best in engineering but also leading the way in its sustainable business efforts, Tideway has committed to delivering this project by minimising its impact on the environment. Using the river as a transport route for materials to and from the site has significantly reduced the need for HGVs on London’s already congested roads, and creates a template for other businesses to use the river as an effective and sustainable method of transport.

The project has led the way in sustainable financing for the construction industry, issuing £1.8 billion of sustainable debt to date. Its funding model is paving the way for private financing to fund public infrastructure for a cost-effective way to modernise the assets on which we rely. And as the beginnings of this new legacy for London’s largest waterway rises from the tides with emerging areas of extended embankments, so too does the possibility of a greener and more sustainable way to build infrastructure.

Environmental responsibility isn’t just part of our job. It goes to the very heart of what Tideway is as a company, and our ambitions and values are broader and more profound than just the simple construction of a tunnel. Not only is Tideway’s work sure to clean up the River Thames for generations to come, but the project’s investment in local communities, its inclusive career opportunities, charity partnerships and education programme will help ensure that the legacy of the Tideway project will be felt by many.