Melbourne water bills won't rise: provider

A Melbourne water provider has ruled out any imminent price increase and will not rely on extra supply from the multibillion-dollar desalination plant, despite a near-record dry winter.

There were no plans to increase the desalination order during the 2017-18 financial year, South East Water spokesman Rupert Posner said on Wednesday.

That's despite Melbourne's dams falling to 62 per cent capacity and putting more pressure on the demand for desalinated water.

"We are not expecting an increase in bills from the use of the desalination plant," he told radio 3AW.

Opposition water spokesman Peter Walsh said using extra supply from the desalination plant water would only lead to higher bills.

"(Premier) Daniel Andrews looks hell-bent on making Melburnians pay even more," he said.

A new threshold set by the Andrews government was a "rip-off", Mr Walsh said.

It requires state water authorities to begin preparing for a drought if Melbourne's water storages drop below 60 per cent by November 30.

Victoria has experienced the driest June since records began in 1900.

July rainfall has also been below average, with 27mm recorded across the state so far compared with the monthly average of 71mm.

If drought preparations are to begin, water authorities could start a range of water-saving measures, including using the desalination plant to its full capacity for the first time since operations began in 2012.

The desalination plant provides about three per cent of Melbourne's water supply - 15 gigalitres.

A government spokesperson said the plant was "an investment in water security".

"The desalination plant is a crucial part of the Victorian water grid, which provides water security and insurance against the effects of population growth and climate change," the spokesperson said.