Our solution

Last updated: 20 June 2018

Our solution

The problem 

The River Thames has always played a central role in the life of London. Its contribution to the economic, social, political and cultural life of the modern-day city is difficult to overstate.

And although the river has played a fundamental role in transforming London into the world’s global city, it has not been untouched.

For centuries, the Thames has been used as a conduit for the removal of the city’s waste, and in the hot summer of 1858, a decision was finally made to rid the river of its burden.

The smell of the Thames had gotten so bad that curtains hanging in the Palace of Westminster had to be soaked in lime chloride to overcome it.

Newspapers of the time (and today’s historians) dubbed the summer of 1858 the ‘Great Stink’.

Londoners, many of whom had lived through devastating outbreaks of cholera, now feared their river.

Compelled ‘by the force of sheer stench’, Parliamentarians passed a bill into law to have the problem fixed.

Sir Joe

The result is a magnificent, 1,100-mile network of sewers comprised of more than 300 million bricks, designed by visionary engineer, Sir Joseph Bazalgette.

In 1858, London was home to two million people. Bazalgette had the foresight to build his sewer system for a population twice that size.

However today, the number of people living in the capital is approaching nine million.

So, while the sewers remain in excellent condition, they lack the capacity to meet the demands of modern-day London.

As a result, millions of tonnes of raw, untreated sewage overflow the system and spill into the Thames each year.

The effect on the river’s fish, birds and aquatic mammals is profound.

Ammonia found in sewage harms many of the Thames’s inhabitants, while the bacteria that feed on the sewage deplete the river of oxygen, suffocating many of its fish.

This is simply unacceptable for the world’s greatest city.

Tunnel route


Our Solution

Tideway is upgrading London’s sewer system to cope with its growing population. Our 25km tunnel will intercept, store and ultimately transfer sewage waste away from the River Thames.

Starting in Acton, west London, our tunnel (the Thames Tideway Tunnel), will travel through the heart of London at depths of between 30 and 60 metres, using gravity to transfer waste eastwards.

The solution in brief

It will run mostly parallel to the River Thames, as you can see from the illustration above. At Limehouse, the tunnel will travel northeast, beneath the Limehouse Cut, to Abbey Mills Pumping Station, and then onto Beckton Sewage Treatment works via the Lee Tunnel, which was opened in 2016.

Once our work is complete at our 24 sites in London, the amount of sewage discharged into the Thames will have decreased by 95 per cent, creating a better environment for London and its inhabitants.

Existing system










N.B. This diagram is for illustration purposes only.
For a more accurate visualisation, please download the chart set


Lee Tunnel and STW improvements

Lee Tunnel and STW Improvements

N.B. This diagram is for illustration purposes only.
For a more accurate visualisation, please download the chart set.


Thames Tideway Tunnel and STW improvements

Tideway Tunnel and STW Improvements

N.B. This diagram is for illustration purposes only.
For a more accurate visualisation, please download the chart set.