Victoria's multi-billion dollar, much-maligned desalination plant has finally begun topping up Melbourne's water storages after years of laying dormant.

Plans for the plant at Wonthaggi were announced in 2007 and its construction completed in late 2012 but it took until Sunday for the first water to flow into the Cardinia Reservoir.

If Water Minister Lisa Neville has her way, much more is to come.

Following in South Australia’s footsteps, Victoria will have a minimum annual water order of 15 billion litres.

“We do need to move past this concept that the desal (plant) is for a crisis only,” she told reporters.

“It is there to avoid a crisis, so a minimum water order makes sure we can do that.”

The minimum order – 10 per cent of the plant’s total annual capacity – will be reviewed every three years.

For now, the desal plant is expected to deliver 50 billion litres, equal to 11.1 per cent of Melbourne’s annual usage.

Production on that order was delayed in December after an underground cable to the plant was damaged as the plant was switched from preservation to production mode.

The plant, estimated to cost between $3.5 billion and $5.7 billion, was left unused by the previous coalition government after being commissioned by the Bracks/Brumby Labor government.

By: Luke Costin