SA Premier Mike Rann and Water Security Minister Karlene Maywald yesterday announced plans for Adelaide's $1.1 billion desalination plant, which they say can be delivered 12 months ahead of the original schedule.

"When tender documents were released, we asked bidders to consider if they could deliver the plant earlier than the initial advised target date of December 2011," Mr Rann said.

Cabinet has approved the short-listed three consortia to design, build, operate and maintain the desalination plant at Port Stanvac.

The three short-listed companies are:

* Addwater – a consortia of Veolia Water and John Holland;

* Water First – a consortia of companies including Degremont, Thiess and Thiess Services; and

* Adelaide Aqua – a consortia of companies including Acciona Agua, United Utilities, McConnell Dowell and Abigroup Contractors.

"I am delighted that all three of the consortia have looked at the logistics of building a desalination plant of the size and capacity that we wanted, and say they have found ways to deliver the project 12 months earlier – by December 2010," Mr Rann said.

"Under this revised timeline, the plant would operate at a lower capacity initially, with water delivery gradually increasing to 150 million litres a day by June 2011.

"The plant will have capability for future expansion by up to 300 million litres per day.

"It will provide Adelaide with one-quarter of its annual water use and is a climate-independent source, providing us with the insurance we need against future climate variability.

"It will be powered using sustainable energy sources."

The desalination plant will the largest infrastructure investment ever in SA.

Mrs Maywald said the short-listed companies would develop detailed technical designs and management plans for the plant, as well as contribute to environmental investigations, approvals, and the development of the Environmental Arial Statement.

"We expect to be able to award the contract to the successful consortia for the plant in March 2009," she said.