Yorkshire Water is set to embark on the latest phase of its work to clean, re-line and re-lay its water pipes in Sheffield as part of a £11 million scheme to improve water quality.

Contractors Balfour Beatty started work on the three-year project in 2008, and recently reached the halfway stage of the having already cleaned, re-lined, and in some cases re-layed over 42 kilometers of some of the company's largest water pipes - known as trunk mains - in and around Gleadless, Norton, Ecclesall, Fullwood, Norton Lees and Malin Bridge.

The next stage of the project will see the company returning to these areas to begin work on cleaning and re-lining some of the smaller distribution pipes.

Project manager Ian Johnson commented:

"It's a big project and we've still got a long way to go yet, but we're making speedy progress, thanks in no small part to the fantastic support and encouragement we've had from customers who understand that the work is essential if they're to continue to benefit from some of the best possible drinking water in the world.

"It was important that we kept work on large and small pipes seperate, as to work on them both at the same time would have meant disruptions to water supplies - something we've worked hard to avoid. By staggering our work this way we also ensure that newly cleaned pipes don't pick up any sediment from pipes which have yet to be cleaned."

Yorkshire Water's Rivelin project involves the restoration of more than 80 kilometers of trunk main in the area, reducing the risk of discolouration in the water supply and enhancing the reliability of the pipes themselves.

Some of the pipes were lined with cement in the 1950's so Yorkshire Water has had to develop a new technique to extract it, cutting it into sections with high-pressure jets of water before dragging it out. The pipes are then coated with a modern, polymeric lining, both improving their capacity and prolonging their working life.