Work has begun on a £2.2 million flood defence scheme to protect Exeter's water supply.

A 600-metres long steel sheet piled wall, ranging from 1.5 meters to 2.4 metres high, will be built around Pynes Water Treatment Works at Upton Pytne, Exeter, to protect the site should the nearby River Exe flood severely.

Around 1,000 cubic metres of earth will be moved during the work as the steel wall is driven into the mudstone some five to six metres below ground. Some of this will be used to create refuge areas for livestock.

In the floods of summer 2007, Mythe Water Treatment Works at Tewkesbury, Gloucester, was flooded. Around 140,000 properties lost their water supply. The clean-up operation, replacement of damaged equipment and supplying clean water to customers cost Severn Trent Water in the region of £25 to £35 million.

Following the floods the Department for Environment, Food and Rural Affairs instructed all water companies to review their sites and take appropriate measures to protect those at risk from flooding.

The scheme at Upton Pyne has been designed to guard the works against a future one in 100-year flood event, plus an additional allowance for climate change. It has been reviewed and agreed by the Environment Agency.

Project manager Mike Court explained: "Pynes Water Treatment Works is at risk of flooding as it is built on the River Exe flood plain.

"A significant flood, like those seen in Gloucestershire in 2007, could significantly damage the works and adversely affect the water supply to Exeter and the surrounding area.

"This crucial scheme will protect our customers' water supplies for years to come."

The scheme has been designed by AECOM Limited and will be built by Dean and Dyball Civil Engineering Limited. It is due to be completed by December 2010. Construction work will not affect the water treatment process.

Pynes Water Treatment Works was built in 1833. It has been progressively updated over the 19th, 20th and 21st centuries.

Pynes supplies up to 60 megalitres of water a day to the residents of Exeter, Crediton and surrounding area. Water treated at Pynes is taken from the River Exe at Bramford Speke.