What else is being done to improve water quality in the Thames? 

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The new Thames Tideway Tunnel is one of several projects which Thames Water is now in the process of delivering – to provide London and its citizens with a sewerage system that’s truly fit for the 21st century and beyond.

Boris Johnson, former London Mayor, opens the Lee Tunnel

Boris Johnson

For example, in 2014 we completed a £675m project to modernise and extend London's five major sewage treatment works at Beckton, Crossness, Mogden, Long Reach and Riverside. Individually, just one of these improvement projects was as big as any upgrade ever carried out on a sewage treatment works, anywhere in the UK. These works can now treat 40 – 60 per cent more sewage – in effect, we constructed brand new sewage treatment works alongside the existing works.

Meanwhile, the four-mile Lee Tunnel is designed to work in conjunction with the Thames Tideway Tunnel, by helping to stop more than 16 million tonnes of sewage mixed with rainwater from overflowing into the River Lee every year. Tunnelling was completed in 2014, and the tunnel started operating in January 2016.

We’re also investigating how it might be possible to install Sustainable Drainage Systems (SuDS) across wide areas of London, to help stop rain water from running straight off hard paved surfaces into the drainage system, and store it or let it soak away into the ground instead. A number of projects have been completed or are under way, and we wand to do many more. 

To learn more about managing rainwater in local, targeted ways in London’s crowded landscape, we have started three pilot projects in Hammersmith, Fulham and Kensington. These include rain gardens to absorb excess water from pedestrian areas, as well as storage cells and attenuation crates under permeable road surfaces, which can store rainwater temporarily before slowly releasing it into the sewers when there is sufficient capacity.

All of these measures are carefully designed to complement the benefits of the Thames Tideway Tunnel, as part of our big plan for dealing with flooding and water quality issues in London.