Warning top Sydney beaches too dirty to swim

Some of Sydney's most popular beaches are a bacterial health risk for swimmers today, after heavy overnight rain flushed polluted stormwater systems into the ocean.

The NSW Department of Planning, Industry and Environment warned it wasn't safe to swim at a string of beaches because of elevated bacteria fears, from Coogee in the eastern suburbs to North Curl Curl Beach in the Northern Beaches.

Bronte Beach was also one of the worst affected beaches, as was Manly, Queenscliff, North Steyne and South Steyne.

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Milder health warnings were issued for Bondi Beach, Clovelly, Gordon's Bay, Maroubra and Malabar, all south of the harbour entrance.

"As a general precaution, swimming at Sydney's oceans beaches should be avoided for up to one day after heavy rainfall or for as long as stormwater is present," the government's Beachwatch warns.

"The most obvious signs of stormwater pollution are water discolouration as well as debris in the water and on the tide line."

Stormwater is the major cause of beach water pollution in Sydney.

When rain falls, pollutants including litter, animal droppings, cigarette butts, oil and silt can enter the stormwater system and be discharged directly into the sea.

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