The utility has switched strategy to combine the major civils and tunnelling works with construction of the advanced water treatment facility at Mogden sewage treatment works under a single main contract.

Thames Water said the switch to a single-contractor delivery model would simplify interfaces and strengthen overall project control.

It has now cancelled the £242m tunnelling competition launched in May last year and plans to start a fresh procurement for the enlarged package before the end of 2026.

Under the latest programme, Thames Water is aiming to submit its development consent order application in early 2027, with the four-year main construction programme starting in 2029.

The nationally significant TDRA scheme forms a central part of Thames Water’s long-term Water Resources Management Plan and has received development funding through Ofwat’s AMP8 settlement.

It will include a 4.2km tunnel driven by a 3.5m diameter tunnel boring machine from Mogden to the Thames upstream of Teddington Weir, together with four shafts. This will return heavily treated water to the Thames replacing abstracted fresh water.

A second 150m long 2.2m diameter pipe-jacked connection will transfer abstracted river water into the existing Thames Lee Tunnel for onward transfer to the Lee Valley reservoirs in East London.

A new tertiary treatment plant at Mogden will treat wastewater before returning up to 75 million litres a day to the Thames during drought operation, replacing water abstracted for London’s drinking water supplies.

Thames Water forecasts London could face a daily water deficit of around one billion litres by 2050 without further action.

Myles Rawstron-Rudd, TDRA Project Development Manager, said: “As London experiences one of the hottest summers on record, it is vital that we plan ahead to protect our water security and ensure supplies are available when they are needed most.

“The Teddington Direct River Abstraction (TDRA) project is a critical drought resilience project for London and a key part of our long-term plan to secure water supplies for future generations.

“Following a period of public consultation, technical assessments and stakeholder feedback, a number of updates have been made to the project design. These changes have improved the scheme’s safety, viability and operability, whilst also reducing potential impacts on local communities and the surrounding environment.

“As a result of this work, we’ve now refined our procurement strategy and will deliver the project through a single construction package.

“This approach will provide greater certainty, stronger project controls and improved programme stability through the appointment of a single principal contractor. It will also deliver overall cost efficiencies for the project while maintaining the planned delivery programme. There will be no delays to the project because of this change in procurement approach.”