We're being assured the water in Warragamba dam is safe to drink despite claims it's been contaminated by green algae.
The algal bloom has spread across 60 kilometres of the dam's surface and is 12 metres thick.
It's claimed none of Sydney's filtration plants have been built to remove algal toxins.
But Water Minister Phil Koperberg says no water is being pumped from the affected area and it's still being filtered properly.
“The advice that we have is that the filtration plant prospect which of course has been recently upgraded, is more than capable of dealing with the algal affected water.