(Nicholas T Ansell/PA)
(Picture: PA Wire)Londoners could be drinking desalinated water from the River Thames next summer under plans to improve supplies during heatwaves.
Sarah Bentley, chief executive of Thames Water, said its £250 million desalination plant, built at Beckton 12 years ago but only used on three occasions, will be back in use next year.
Fresh water from the Thames, taken upstream of Teddington, is already used for drinking water supplies. But the desalination plant will also allow saline water downstream of Teddington — a stretch known as the Thames tideway, where the water is similar to sea water — to be used.
It came as the company announced the completion of 15.5 miles of tunnelling to create a “super sewer” under London to prevent the Thames being deluged with discharges of sewage after a downpour.
Desalination involves taking “brackish” water from the Thames estuary and forcing it at pressure through tiny membranes to remove the salt content.
But the process is energy intensive and requires minerals to be added to the “pure” H2O that results from the process to enable it to be consumed.
A hosepipe ban introduced by Thames Water in August, banning its 15m customers from watering gardens or washing cars as it sought to conserve supplies after this summer’s record 40C temperatures, remains in place.
Ms Bentley said the desalination plant was only planned as a “swing site” for intermittent use, able to supply 100 mega-litres a day – five per cent of the capital’s needs.
She told the Standard: “It was operational in time for the Olympics. It’s been operated three times – it was never built as a permanent site.
“Because of all the dry weather we have been having, we have been investing to get it operational again.
“It’s a fascinating project but it needs a lot of maintenance. With all the dry weather and the risk of drought, we want that working for next summer.”
The super sewer, known as the Thames Tideway tunnel, stretches from Acton to Abbey Mills pumping station in east London.
It will act as the “world’s biggest storm tank” when run-off water from thunderstorms threatens to overwhelm the capital’s existing Victorian sewers, built 150 years ago by Joseph Bazalgette.
The final “drive” to Abbey Mills has been completed and engineers are now lining the 7.2m-wide tunnel and adding a secondary concrete lining.
It is due to be brought into use by the end of 2024 and should reduce sewage spills into the River Thames by more than 95 per cent.
The Lee tunnel, part of the project, has already been used 37 times – preventing sewage from entering the river.
Thames Water customers have begun paying a premium on their bills of about £20 to £25 a year over the next 80 to 100 years to fund the super sewer’s construction.
“This isn’t about replacing Bazalgette’s amazing infrastructure,” Ms Bentley said. “This is about extending the life of it.”
A legacy of the construction work will be the creation of nine public spaces, seven of which will be in the “foreshore” of the Thames, including at Blackfriars, Chelsea and Putney.
Ms Bentley, who is under pressure to reduce leaks across Thames Water’s infrastructure, called for the preservation of water to become as important as reducing carbon emissions, and for less concrete to be used to improve London’s “spongification”.
This involves retaining front gardens and green spaces to allow rainwater to seep through to underground reserves.
