Melbourne's water storage level had fallen to its lowest point in nine years, Acting Premier John Thwaites warned today.

Mr Thwaites, the state's water minister, appealed to Victorians to conserve water, with new figures showing the city's reservoirs were down to just 38.7 per cent of capacity.

The 0.4 percentage point drop since last week means the total capacity of Melbourne's reservoirs is 19.5 per cent down on this time last year, despite lower than average water consumption in the past week.

Mr Thwaites said he was not surprised by the disappointing statistics.

"The amount of rain has been extremely low but more important than that, the stream flow into our reservoirs is about 40 per cent below the lowest ever, so we are in uncharted territory in terms of water supply to our dams," he told reporters today.

"The stream flow from July to October in all parts of the state was the lowest ever by a very big margin so, obviously, the amount of water in the reservoirs is considerably lower.

"Obviously, we are all desperate for rain. I think the whole of south-eastern Australia - Queensland, NSW and Victoria - and parts of south-western WA until the past few days, have had way below their average rainfall."

Mr Thwaites said Victorians needed to pull together to cope with the water crisis.

"This means that recycling needs to be boosted. It means that we have to reduce leaks in the system and it means that all of us have to conserve water, so it's a complete, comprehensive strategy that we have to adopt," he said.

Stage Three water restrictions in place in Melbourne include a ban on the watering of lawns and washing cars with hoses.

AAP