A WATER treatment plant which supplies more than 30,000 homes in North Yorkshire is to be improved at a cost of millions of pounds.

Yorkshire Water is to spend £6.5m on improving the quality and reliability of the supply from its Thornton Steward works, in Lower Wensleydale, which should increase output from the plant by ten million litres a day.

The site is to be upgraded to cope with anticipated demand from additional housing, including the expansion of Catterick Garrison.

The plant supplies 31,500 customers in the Lower Wensleydale, Catterick, Richmond, Thirsk and Northallerton areas, which are earmarked in the county plan for housing development.

The work will see output increase from 23 million litres a day to 33 million litres.

The project is due to be completed by autumn next year, although some improvements should be made by spring.

Older plants at Langthwaite, in Arkengarthdale, and Osmotherley, near Northallerton, will be mothballed and there are plans to eventually close the treatment works at Kepwick, near Thirsk. There will be no job losses as a result of the closures.

Project manager Peter Riggall said: "Thornton Steward is now linked to the supply of an estimated 31,500 customers across the north of North Yorkshire so it makes sense to ensure it's of the highest standard.

"The upgrade also allows us to decommission some of our older plants in the area which should help improve efficiency."

The contract for the construction work was awarded to Earth Tech Morrison (ETM), of Wakefield, to design, supply, install and commission the plant, which will include a dissolved air filtration plant, rapid gravity filter and sludge presses.

"Water supplies should not be affected and we would urge customers to be on their guard if they find strangers knocking on their doors claiming to represent Yorkshire Water or ETM," said Mr Riggall.

"We do not anticipate needing access to properties in the area but, if we do, genuine employees carry identity cards which can be checked by telephoning 0845 124224, and they won't mind waiting while their details are verified."

Yorkshire Water has already spent £3m connecting Swaledale to the Yorkshire netwrok, which improved water quality and reduced the risk of interruptions to supply.