Five surfers suffering from severe ear infections will seek damages from South West Water and Southern Water when proceedings begin next month.
The onus will be on them to prove that the illnesses have been caused by untreated effluent discharged off the Cornish coast.
But if the surfers win, the water companies could face hundreds of actions. Surfers Against Sewage's general secretary, Chris Hines, claims that his association alone has had 300 members suffering from pollution- related sicknesses.
The five litigants include a 14-year-old boy, Justin Skelton, who has been dogged by recurrent ear infections for three years.
Justin and three of the other alleged victims claim that they became sick after surfing expeditions from the Cornwall beaches of Porthtowan and St Agnes, which lie between St Ives and Newquay.
Chris Hines said: "There is five million tons a year of raw sewage going into the sea within five miles of Porthtowan and the pipe from St Agnes village goes straight into the bay below.
"For a long time we have been warning the water companies and the Government that their standards are too low and their tests inadequate."
South West Water said it could not comment on a case before the courts but acknowledged that raw sewage was being dumped.
"We inherited 227 crude sewage outlets all over Devon and Cornwall when we became a private company," said a spokesman.
"It is a big job catching up on a century of neglect."
South West Water has asked the Monopolies and Mergers Commission for permission to push up its bills yet higher to meet the cost of cleaning up the beaches. To conform with European Union rules, the company plans to treat the sewage by allowing biological agents to break it up and then to dump the effluent out at sea through long discharge pipes. It says it will comply with the EU standards by 2000.
However, Surfers Against Sewage argues that it is cheaper and safer to destroy all viruses by exposing the sewage to ultraviolet light before it is dumped. The pressure group claims that the EU benchmarks are not good enough.Reuse content