Thames Water has played down fears that it is to abandon a 12km length of the Thames Tideway tunnel in favour of diverting flows along an alternative route.

Reports from engineers close to the project said that the length of the 32.2km tunnel could be cut short and the flow diverted into the Lee Tunnel in a bid to save money.

“We have not yet had the public consultation so until then we are open minded on the route and we can’t discount anything,” said a Thames Water spokesman. A public consultation on the 32.2km project is expected to begin in Summer 2010 with the final scope of the scheme determined after this. “We can’t rule it out but it doesn’t mean it is likely to happen,” said the spokesman.

The Thames Tideway project consists of two tunnels. The first is a major 32.2km bore, with a 7.2m internal diameter, that follows the path of the Thames collecting spillages from 36 sewer overflows. It starts at Hammersmith in West London and terminates at Beckton Sewage Treatment Works in the east. The second is the 7km Lee Tunnel which begins at the Abbey Wells pumping station and also terminates at Beckton.

According to reports the water company is considering terminating the main Thames tunnel just east of the Tower of London and diverting the flows to the Abbey Wells station where it would then join the Lee tunnel. This would shave approximately 12km from the route.

Thames Water confirmed that construction of the Lee Tunnel is still on schedule to begin in April 2010 and appointment of the contractor is planned for the end of the year. Two companies are competing for the £430M award, a joint venture of Morgan Est with Vinci Construction Grands Projets and Bachy Soletanche; and Murphy with Hochtief.

Construction of the main tideway is scheduled to begin in 2012 following public consultation and planning approvals. The project should be completed by 2020.

The cost of the scheme is still unconfirmed but is expected to be in the region of £2bn. However Thames Water is under pressure to cut its spending plans after industry regulator Ofwat determined that it should invest £4.6bn across its water and waste water network between 2010 and 2015. Thames Water wanted to spend £6.5bn. A final decision on its spending limits will be made by Ofwat this month.