Extremely low rainfall in regional Victoria means the switch could finally be flicked on the state's controversial $6.1 billion Wonthaggi desalination plant.

The plant has produced no water since it opened in 2012, but dam levels have fallen by 130 billion litres over summer, which is 2.5 times the average summer loss for the past five years, Melbourne Water says.

Melbourne’s dams are at 64 per cent capacity compared to 71.5 per cent in November 2015.

desal

Storages are expected to continue their decline in autumn, with the Bureau of Meteorology’s three-month forecast showing a high likelihood of below-average inflows at all four major reservoirs.

A spokeswoman for Water Minister Lisa Neville said the government would make an announcement in the “coming weeks” about whether the desal plant would be fired up.

“The government has always said that the desalination plant is our insurance policy for drought (and we) will consider the advice of the water corporations,” she said on Tuesday.

Victorians pay $1.8 million each day for the plant to sit idle.

HOW MUCH IS THE WONTHAGGI DESALINATION PLANT COSTING YOU?

THE PLAN

  • A $3.1 billion, 150 gigalitre plant announced in 2007 to drought-proof Victoria

THE BLOWOUTS

  • Cost increased to $3.5 billion, then $4 billion
  • Auditor-General said the net present cost was $5.72 billion
  • Department of Sustainability and Environment costs added to a final $6.1 billion figure
  • PricewaterhouseCoopers said it will cost up to $23.9 billion over the life of the contract

THE WATER

  • Victoria’s drought ended as the plant was completed
  • No water has ever been ordered from Wonthaggi
  • It costs water customers $1.8 million every single day for the plant to sit idle
  • Contract set to expire in 2039.