VILLAGERS who spent years swatting up on water industry expertise have now pledged to pick apart plans for a colossal reservoir with their own technical knowledge.

Action organisation GARD (Group Against Reservoir Development), which has battled for years against Thames Water's proposals for an "Abingdon reservoir", said it would scrutinise the idea based on solid research rather than personal opinions.

At an annual meeting on Monday, committee member Wren Wooster said: "We are not going to rely on their consultancy – we are really going to have to pick this apart ourselves."

Since 1975, the water provider has floated hopes to build the reservoir between Steventon, East Hanney and Drayton, providing up to 150 million litres of water a day to save London from future drought.

It is currently researching revised plans for the project using computer modelling – a method mimicked by GARD's very own hired expert John Lawson.

Committee member Nick Thompson said: "GARD has a big battle ahead. John has put Thames Water on the spot by doing his own modelling.

"Without him we would have been incapable of putting up the necessary technical challenges to Thames Water's work."

He said criticism based on the reservoir being an eyesore would not wash with Thames Water.

Derek Stork, who stepped up at the meeting as new chairman, said: "They will confuse us with facts as much as they possibly can.

"GARD is taken quite seriously. When I went to a Thames Water meeting I was watched like a hawk and allocated a minder."

The group, which won a public inquiry against the reservoir in 2010, favours a desalination plant to solve the water shortage that would recycle used water.

In a 2014 briefing paper Thames Water said a desalination plant "is over double that of the least cost option", but GARD said their calculations were based on running it for a longer period each year than necessary.

Martin Wells, a spokesman for Thames Water, said: “The comprehensive water resource planning process that any proposal for a new reservoir or any other new water resource has to go through will allow ample opportunity for a scheme to be subjected to rigorous challenge and scrutiny, as part of the statutory process.”