SOUTH Australian irrigators have applauded a State Government decision to return 20 billion litres of water to the River Murray.

Premier Jay Weatherill yesterday announced SA Water would sell the water to the Federal Government for environmental flows, easing the burden on river communities faced with relinquishing large quantities under the Murray-Darling Basin Authority's proposed plan.

It followed calls in The Advertiser yesterday for Adelaide to play its part in returning water to the river.

Central Irrigation Trust chief executive Gavin McMahon said the sale would save the equivalent of 2000 hectares of wine grapes. That equates to an irrigation district the size of Barmera.

"We're very happy that the city is prepared to play their part," Mr McMahon said.

"That's quite an amount of water that doesn't have to come from our communities."

The 20 billion litres comes on top of 79 billion litres that has already been recovered from water purchases from irrigators.

The state has also returned a further six billion litres in exchange for the Federal Government's contribution to the Port Stanvac desalination plant.

SA irrigators are attempting to unlock about $240 million in federal funds for infrastructure upgrades they believe will save between 20 billion to 40 billion litres.

The MDBA's plan calls for an SA return of 101 billion litres.

That number is likely to increase to about 160 billion litres once a further 971 billion litres in savings are identified across the basin.

Mr Weatherill said the SA Water contribution sent a message to the state's irrigators that "we stand ready to back you in and do our fair share".

Mr McMahon said 20 billion litres would fetch roughly $34 million on the water market.

Treasurer Jack Snelling said the proceeds would probably pay down SA Water's debt.

Mr Weatherill said SA's reliance on the river had been reduced in part by the increased rainwater use in SA households.

"Recent figures indicate that 49 per cent of households in SA use rainwater tanks compared with 26 per cent nationally," Mr Weatherill said.

"We are doing our fair share to restore health to the river." - with Greg Kelton