Mr Hunt said comments by the premier that he would "prefer" that the powerlines were placed underground were "downright devious" and designed to confuse the public.

"Responsibility for pushing ahead with the most expensive, environmentally destructive option for securing our water supply at the expense of other, more sustainable options rests solely with the premier," Mr Hunt said.

"Was Mr Brumby saying that he hoped for underground power but that the final decision was out of his control? Did he mean to imply that he did not have the authority to rule on this issue?"

In May, Mr Brumby announced the Government's preferred power source as underground electricity with a supply route aligned to an existing overhead powerline easement at Pound Road, Clyde North.

The route would then connect to an existing terminal station in Cranbourne.

Mr Brumby said an overhead route, not the Government's preferred option, would be a northerly connection from Tynong North to Woolamai.

An announcement of the successful bidder - of two private consortia BassWater and AquaSure - is expected in the coming months.

Mr Hunt called on the Premier to rule out the use of an overhead power source and avoid erecting powerlines through fertile farmland and spectacular coastal scenery.

"Better still, he should scrap plans for the desalination plant altogether and focus his energies on wastewater recycling."