The Lee Tunnel, currently the biggest single project in the history of the privatised water industry in England and Wales, has been delivered on time and on budget.

By increasing capacity in the sewer network the tunnel will carry the excess sewage, which has previously been discharged to the River Lee, to Thames Water’s Beckton sewage works in Newham for treatment, with renewable energy being generated from the by-products known as sludge.

In a typical year, 39 million tonnes of untreated sewage mixed with rainwater has been discharged into the River Thames from overloaded treatment works and combined sewer outfalls. The biggest of these outfalls, at Abbey Mills pumping station, has been discharging 16 million tonnes of sewage to the River Lee in a typical year. The Lee Tunnel will capture the polluting sewage and keep it out of the river, which will become much cleaner.

The Lee Tunnel is the largest single project in the history of the privatised water industry in England and Wales and is the deepest ever bored under the capital at around 75 metres deep. 

Alongside major upgrades already completed by Thames Water at its five main sewage works along the tidal River Thames, the Lee Tunnel will transform the quality of the River Thames and River Lee for river users, wildlife and those who live and work in the capital for generations. Construction on the Thames Tideway Tunnel, which will connect to the Lee Tunnel, will start later this year.

 The Mayor Boris Johnson, in partnership with Thames Water, the Environment Agency and London Councils recently launched the first London Sustainable Drainage Action Plan, identifying potential flooding hotspots across the city and proposing innovative ways of diverting rain back from the sewers into the soil with rain gardens or green roofs.

Boris Johnson MP said:

“This amazing new super sewer is providing the bold infrastructure needed to support the movements of our rapidly growing city. For years our historic Victorian systems have heaved at the seams, muddling along, battling to cope with the increasing rainfall and waste of a modern population. Now the River Thames will benefit from vast improvements to its water quality with less pollution and overflow. Alongside my sustainable drainage work to reduce flooding, the investment in the Lee and the forthcoming Thames Tideway Tunnel are set to benefit Londoners for generations to come.”

 The £678 million Lee Tunnel runs 6.9km from Thames Water’s Abbey Mills pumping station and will act as a collection and storage tank before transferring the flows to Beckton sewage works, which Thames Water has expanded by a further 60 per cent to manage the increased volumes.