Travelling to Sydney? Think twice before taking a dip in the harbour

Swimmers taking to the waters off Sydney's eastern suburbs could be exposed to "very high" health risks because untreated sewage is being dumped straight into the ocean.

A new Sydney Water report has found three sewage outfalls in Vaucluse and Diamond Bay - which discharge untreated wastewater into the ocean - expose people in the immediate vicinity to "very high" health risks.

The report, published this week, found the waters weren't suitable for swimming even though about 2000 people a year use the area for swimming, spearfishing and scuba diving.

While water quality at nearby swimming beaches such as Bondi remains "good" or "very good" people in primary contact with the contaminated waters near the outfalls are exposed to "significant risk of high levels of illness transmission," the report said.

Sydney Water has erected signs advising people not to swim in the immediate vicinity of the outfalls.

"These three outfalls are a legacy from Sydney's early wastewater network and while there's no easy way to fix them, we take our responsibility to protect the environment and public health very seriously," Sydney Water's managing director Kevin Young said in a statement on Thursday.

The three outfalls built between 1916 and 1936 are the last remaining untreated discharge points in NSW.

They include sewage from more than 10,500 people living in Watsons Bay, Vaucluse, Diamond Bay, Rose Bay North and parts of Dover Heights.

People who come in contact with the polluted water risk developing skin, gastro and respiratory infections, the report said.

The outfalls also threaten marine ecosystems by reducing habitat availability through exposure to solid pollutants such as toilet paper, sanitary products and wet wipes.

Sydney Water will in April commence community consultations to identify the best solution for managing the sewage releases.

Vaucluse MP and NSW Environment Minister Gabrielle Upton believes it's important to find a solution which benefits the environment and the community.

"I'm reassured Sydney Water is talking to the community first and that they will look a range of technological advances to see how to get the balance right," she said in a statement.

Woollahra Council is looking forward to participating in the consultation process, a spokeswoman told AAP.

Cityscape view of Sydney, Australia in evening.
Sydney (file picture). Source: