Swimmers have been urged to stay away from some of Melbourne's most popular beaches after Thursday's torrential downpour caused sewage and built-up pollution to stream into Port Phillip Bay.
On Friday, the Environmental Protection Authority deemed tourist hotspot St Kilda beach unsafe to swim in.
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Melbourne's 'one-in-100-year' storm
Homes flooded, rivers gushing and cars floating away - all scenes from Friday's massive downpour across Melbourne and the aftermath on Friday.
Other beaches around Williamstown, Elwood, Brighton, Frankston and Werribee South were also harbouring dangerous bacteria after the "one-in-100 year" downpour caved in ceilings and flooded homes.
While beaches closest to the city were the worst affected by Thursday's downpour, the string of beaches along the Mornington Peninsula did not escape unscathed.
The peninsula scraped by with a "fair" rating by the EPA. This means beaches such as Sorrento and Rye may not be suitable for swimming.Â
St Kilda beach was crowded with tourists, families and couples enjoying the warm weather on Friday afternoon.
Despite prominent signs announcing the beach was closed, several people could be seen in the water.Â
Most of the signs did not explain the reason for the closure. One sign did say the water quality was poor.
German tourist Sabine Ranft was taking a dip with her three-year-old daughter Josie.
Ms Ranft said she didn't know the water was dirty.Â
"We are getting out of it right away," she said.
Ms Ranft said the sign didn't really explain why the beach was closed.
"I thought it was because of water sports," she said. "It is very misleading."
Irish tourist Beth McAllister said she had spent about 20 minutes in the water.
She didn't know that it was dirty, but knew the quality was bad once she got in.
"It smelt bad," Ms McAllister said.
She said she didn't understand the sign which simply said the beach was closed.
#BeachReport & #YarraWatch forecast: POOR at 6 Melbourne beaches and along the Yarra. Avoid contact with water. pic.twitter.com/8M8R8zi3AW
— EPA Victoria (@EPA_Victoria) December 29, 2016
The beaches around Geelong were given the all-clear.Â
EPA group manager Dr Anthony Boxshall said people should not swim in beaches for up to 48 hours after heavy rain.
This is because it generally takes the bay two days to recover.Â
"This holiday season many people will be spending time in the water and we want to make sure they don't get sick," he said.
"Everyone should be checking the forecast before they go swimming."
Authorities are urging beachgoers to monitor the EPA's Twitter feed and their local surf lifesaving clubs for water quality updates. In a cruel twist, the EPA's website was experiencing issues on Thursday.