RAW sewage has been regularly discharged in the sea off Dorset’s award-winning beaches over the last few weeks because of recent wet weather.

Campaigners are now calling for the practice to stop, claiming that bacteria and viruses in the sewage threaten the health of surfers, swimmers and other water users.

Combined sewer outflows (CSOs) act as relief valves in heavy rain, carrying a mixture of surface and foul water into rivers or the sea.

Although those that discharge into designated bathing waters should only go off three times a year at most, Wessex Water’s records show several in Dorset were repeatedly triggered – sometimes for several hours at a time – in a single week.

Bournemouth and Boscombe Piers, Hengistbury Head, Sandbanks, Avon Beach at Christchurch, Swanage, Rockley Sands in Hamworthy, Lodmoor in Weymouth and Charmouth in West Dorset were all affected between June 4 and 13.

The blackspot was Avon Beach, where the outflow was set off a dozen times during the week – on one occasion apparently discharging diluted sewage for nearly 25 hours on June 7 and 8. Its monitoring equipment is now being checked.

Purbeck-based environmentalist Steve Trewellha said: “Every time it rains, we’re ending up with completely untreated sewage in the sea. It doesn’t clear up that quickly. The issue is sewage-related pathogens in the water, such as e-coli.

“Putting the pipe out to sea doesn’t make it go away. CSOs normally go off in winter when there aren’t many people in the water, but it’s June now and they’re still going off.”

Researchers at San Diego University found one cigarette butt contaminates 7.5 litres of water badly enough to make it lethal for marine life.

Andy Cummins, campaign director of Surfers Against Sewage, said water quality standards were “woefully outdated”.

He pointed out that hepatitis A could survive for 90 days in salt water and e-coli for 30 days.

Even at beaches meeting the highest standards, surfers had a one in 20 chance of contracting gastro-enteritis.

A spokesman for Wessex Water said: “Our overflows are licensed to operate by the Environment Agency. The licence specifies how much flow must pass through the system before a spill occurs.

“The flows are very diluted.

“In the last three years 36 out of 37 south coast beaches in the Wessex Water region have met the highest water quality standards.”

Alan Brown, Bournemouth Council’s Seafront Operations Manager, said: “The latest bathing quality report from May 25 shows that our bathing waters meet the most stringent guideline standards – therefore we have no concerns at this time.”

What you said

George Shepherd, 67, visiting for the day from Salisbury, a retired RAC worker, said: “It’s nothing to worry about. I have been in the sea today.

“I don’t think the pollution is that bad from what I have seen. I can understand why people are concerned but I have seen nothing untoward.”

Callie Eveson, 9, visiting for the day from near Dudley, said: “I worries me because if the water gets really dirty you could ill.

“The water seems nice though. I think the company should be building more sewers.”

Lorraine Higham, 53, down for a fortnight from Ledbury, said: “I don’t think they should be putting it into the sea. I think they should be keeping it clean.

“It looks quite clean around there though and I think the risks are probably quite low. I would still go in.”

Alice Bowen, 21, from Wimborne, a trainee teacher, said: “I think the Wessex Water plant is overworked. I used to go to school next door and it absolutely stinks.

“They probably need more investment in their system. It’s a health concern for families using the beach.”