Balfour Beatty, Costain, Skanska and Laing O’Rourke are all believed to bidding for the work.
US consultant and contractor Black & Veatch, which bought MJ Gleeson’s water business in 2006, is interested in the Mogden part of the project only.
Thames Water, which is chaired by former Amec and Balfour Beatty chief executive Sir Peter Mason, has divided the work into three lots with the first, worth £70 million, focusing on Mogden in south-west London.
This includes new inlet works, aeration blowers and expansion of the existing sludge treatment facilities. The work is expected to take four years.
The second lot, worth £180 million, requires extensive work to the Crossness sewage treatment facility in Abbey Wood, east London, which covers a catchment area of 240 sq km including Richmond-upon-Thames, Wandsworth, Merton, Lambeth, Southwark and Lewisham.
As well as providing facilities such as a new washwater pumping station, circular final settlement tanks and raw sludge buffer tanks, the winning contractor will also need to provide wind turbines to supply renewable energy for the plant.
Contractors can bid for either lots one and two or opt for lot three, which bundles both packages up into a £250 million contract.
A Thames Water spokesman said: “We’re waiting for the bids to come in and we’ll be expecting to make a decision next February. Work will start soon after.”
The projects will be well underway once construction of the first phase of Thames Water’s flagship £2.2 billion Thames Tideway project begins next March.
Before the main 32 km-long tunnel linking Hammersmith in west London and Beckton in east London is bored, the smaller Lea Tunnel, which will run for 7 km and have a diameter of 7.2 m, will be built.
It will pass under the original northern outfall sewer as well as below the recently built lower Lea Valley cable tunnels, lying within the upper chalk layers at depths of 60 to 75 m.
The project will be managed by US consultant CH2M Hill, which is a member of the CLM team making sure the 2012 Olympics venues get built.