Campaigners fear a Brighton water supply could be ruined forever if a park and ride scheme goes ahead.

Engineering specialist Dr James Rhodes warned that Brighton and Hove could suffer the same fate as Santa Monica, California, which has been importing 95 per cent of its water since 1995, when the supply was polluted by leaking underground petrol storage tanks.

Dr Rhodes, a former Brighton University lecturer, said the same thing could happen if Brighton and Hove City Council granted permission for a 900- space car park at Patcham Court Farm or Braypool playing field.

He said oil and petrol leaking from cars would be stored in holding areas around the car park but would spill over whenever Patcham suffered one of its frequent floods, contaminating water stored in the aquifer, porous rock from which Southern Water extracts up to 17.5 million litres of water a day.

Dr Rhodes made the claim at a public meeting organised by Patcham Against Insensitive and Destructive Development (PAIDD) at Patcham Community Centre in Ladies Mile Road on Saturday.

He said tests of the ground water at Patcham had found it already contained traces of DDT, arsenic and de-icing chemicals.

If the park and ride scheme was allowed to go ahead at Braypool playing fields, across the road from Patcham Court Farm, the RSPCA will lose a centre where it looks after more than 3,000 animals every year.

The Patcham Court Farm site is occupied by six homes, 35 allotments and derelict farm buildings.

Masa Kepic will lose her home if the car park is built there.

She said: "From every possible viewpoint, this is a ridiculous idea."

She said she would be prepared to protest by blocking traffic heading into the city and called on other campaigners to join her.

She said: "I would be happy to be the first person blocking the road into Brighton. I was at the Twyford Down road protest when I was at university and we successfully stopped traffic for an hour. I am quite prepared to do that again and I hope plenty of other people would join me."

Allotment holder Granville Wilcock said there were more than 30 people on the waiting list for plots at Patcham Court Farm.

The park and ride proposal will be discussed by Brighton and Hove City Council's policy and resources committee at 4pm on Wednesday, October 19.