Australian beaches are very clean most of the time, including beaches within metropolitan Sydney.
Beachwatch and Harbourwatch pollution monitoring of Sydney's beaches from Palm Beach south to Cronulla shows that water quality is safe for swimming at all beaches, virtually all of the time. When it rains heavily it's a different story. Pollution from stormwater and sewer overflows can make beaches unsuitable for swimming and surfing for 24 hours at ocean beaches and for at least three days in harbour beaches and other estuarine areas, such as the Lower Georges River. You are the best person to decide when it is safe to swim at a particular beach. Our changing weather means that swimming conditions at the beach can vary throughout the day and from one day to the next.