Supersewer? Think again, says US city that has one

Thames Water's plan for a London supersewer has come under fire from a US city which built a similar tunnel.

Alderman Willie Hines, the president of Milwaukee Common Council, said Thames Water should learn from its problems.

The project manager of London's planned £3.6 billion Thames Tunnel said Milwaukee's deep water tunnel was the example to follow. Officials in the US city say its $1.2 billion tunnel has cut the amount of sewage dumped into its main river by 85 per cent and improved the quality of water.

However, it has emerged that the tunnel has also caused residents' basements to flood and failed to stop sewage overflows. Mr Hines said that with hindsight a "supersewer" would not be top of his shopping list. He said: "I would look at it as part of the comprehensive strategy but it would be the third leg. If I were in London's situation, I would learn from Milwaukee."

Supersewer project manager John Ramage said Wisconsin had seen at least two severe storms in 17 years and the sewer "performed exceptionally". But residents who have had their houses flooded say the scheme has not worked.

The 20-mile Thames Tunnel broadly follows the river and will collect sewage discharge triggered by rainfall.

Thames Water said: "Milwaukee's tunnel did what it set out to do - significantly reduce sewage discharges to the river. A decade of independent study has shown that the Thames Tunnel is the best way to significantly tackle the 39 million tonnes a year of sewage that overflows to London's river."