The news of cleaner beaches has been welcomed

South West Water said that its Clean Sweep programme, costing �1bn, had helped bring about the improvements.

But environmental campaigners said the standard of testing is not stringent enough and regulations are about 30 years out of date.

The beach that failed the water tests was Instow in north Devon. Raw sewage was found on it, say owners.

Instow beach is privately owned. The Environment Agency said pollution there was caused from agricultural run-off from fields.

The programme has removed over 200 crude outfalls that used to discharge around the coast Stephen Bird, South West Water

But its owners believe the pollution is coming from raw sewage.

Raymond Coldwell of Christie Estates said: "They constructed a sewer in this area, which should have resulted in this problem being eliminated.

"The fact that continual pollution occurs at Instow is of grave concern to parishioners and villagers alike."

South West Water (SWW) said it was down to Clean Sweep that so many improvements had been made in bathing water quality.

Cleaning up beaches has been very expensive

SWW Operations Director Stephen Bird said: "The programme has removed over 200 crude outfalls that used to discharge around the coast. We now have 40 state-of-the-art treatment facilities, many of them with UV disinfection."

But environmental campaigners say the water still is not clean enough.

Richard Hardy of Surfers Against Sewage said: "At the moment the bathing water directive is 30 years out of date. It doesn't really represent the true risk to public health."

The Consumer Council for Water welcomed the news of so many beaches achieving the standards, but said the Clean Sweep programme had been hugely expensive.