The Premier Jay Weatherill has gone back to the future with Labor's first election campaign pledge — promising to "decorporatise" SA Water to protect state-owned water and electricity assets from privatisation.

Mr Weatherill told the ALP's state convention in Adelaide that a re-elected Labor government would create a new department known as Energy and Water Services (E&WS).

The name is an obvious play on the former Engineering and Water Supply Department, which was abolished in the 1990s when SA Water was created to operate as a government business.

Mr Weatherill said the new department would be responsible for managing SA Water's water and sewerage assets, along with state-owned energy assets like the Government's proposed 276 megawatt gas-fired back-up generator.

"We believe it's time for the Government to step back in and play a much bigger role in both electricity and water and that's why we're creating this new department using the old name of the EWS," Mr Weatherill said.

"It's a place where we'll hold our essential services assets, so our new state-owned power plant and our water and sewerage assets.

"We want to protect them from privatisation because we believe holding them in public hands is the best way we can protect consumers."

Earlier this week, Opposition leader Steven Marshall announced a Liberal government would not proceed with the purchase of the state-owned power generator, and would instead seek to pay private generators to reserve spare capacity.

Mr Weatherill said a Labor government would create legislative protections to make it harder for a future governments to privatise water or electricity assets.

Privatisations in South Australia

That's despite a suite of privatisations conducted during Mr Weatherill's premiership including forestry, lotteries, the Motor Accident Commission and the Lands Titles Office.

"The Liberals are addicted to privatisation, and no doubt SA Water will be up for sale if they ever get the chance," Mr Weatherill said.

"At the next state election, South Australians will have a clear choice: a Labor government which will keep essential services in the hands of South Australians, or a Liberal government which would privatise our assets."

Mr Weatherill said the new department would be able to take advantage of increasing synergies between energy and water, including technologies such as pumped hydro, floating solar panels and generating electricity from biogas at waste water treatment plants.

The South Australian election will be held in March.