WRONGLY connected drainpipes, dog mess and heavy rain have been blamed for high bacteria levels in Swansea Bay.

The bay was one of six beaches in Wales which failed European Council (EC) guideline standards this summer, although they all passed a less stringent EC bathing water test.

Beaches elsewhere in the region, such as Oxwich Bay, Port Eynon, Rhossili, Pendine and Aberavon, passed both tests.

The Post has seen the results of weekly water sampling by the Environment Agency at Swansea Bay, taken opposite the Patti Pavilion from May to September. The agency measured bacteria levels which indicate human and animal faeces, with six failures throughout the 16-week period — badly connected waste pipes at home was a factor.

Leakages from dumps and old mines have also had an impact on the quality of water.

Hamish Osborn, environmental management team leader at the agency, said failures occurred after heavy rainfall, when large plumes of "fresh" water discharged into the bay.

This water, from the River Tawe and streams like Cwm Stream, which runs through Sketty and Derwen Fawr, picked up pollutants.

Mr Osborn said some homes had wrongly connected drains, perhaps after extensions had been added, sending unpleasant waste into water courses.

The agency, Swansea Council and Welsh Water are investigating the problem.

"We are looking at pollution in small streams and storm drains and tracing them to housing estates, but it's a bit of a needle in a haystack," said Mr Osborn.

Water quality was better in Swansea Bay than in the past, he stressed, although the recent wet summers had reversed that trend. "If we have good weather, then it's relatively easy for a beach to perform quite well," he said. "Dog mess does have an impact, which is part of the reason we have dog bans on beaches." Some leachate is still leaking out from the old Clyne rubbish dump in Derwen Fawr, said Mr Osborn, but work has taken place to divert it into sewers rather than the Clyne River, which is also affected by mine water from old collieries in the Dunvant area. Swansea Council takes samples from the Clyne River and at Blackpill.

A council spokesman said the 2008 samples were consistent with "heavy bacterial loading after heavy rain", but all had passed the mandatory standard.

In Wales, more beaches passed the stricter EC guideline standards this year than last.

"Ensuring our beaches continue to have excellent water quality is key," said Environment Minister Jane Davidson.

richard.youle@swwmedia.co.uk