Thanet Council stressed the tests were carried out weekly

Sea water is monitored weekly by the Environment Agency during the summer and beaches at Margate, Broadstairs, Pevensey, Bognor and Sheerness failed.

The agency said pollution was caused by rainwater running over roads and fields where it can pick up manure and slurry that runs into drains and into the sea.

Bathers are being advised not to go in the sea at the beaches for a few days.

'Flash floods'

The agency said: "Wet weather and stormy conditions still increase the risk of pollution of our beaches and we are working with water companies to address this to provide safe, clean, bathing water throughout the season."

Thomas Bell, from the Marine Conservation Society, said: "What we are saying is after heavy rain fall - after these big flash floods - we suggest people avoid swimming for a day or two to allow the pollution to disperse and to drift away.

"Other wise there is an elevated risk in terms of contracting things like stomach upsets or ear nose and throat infections."

Brian White, from Thanet District Council, "The water is clean and it is safe.

"It is important the public realise the bathing water is sampled every week during the bathing season.

"We classify results into three groups - excellent, satisfactory and poor.

"The last poor result we had in Margate was in 2001.

"But we working with our partners at Southern Water and the Environment Agency we want to get as many of our satisfactory samples into the excellent category."