South Australian Murray Irrigators chairman Tim Whetstone said today that the federal government's $3 billion buyback timeline would have a catastrophic impact on water prices for South Australians.

"We recognise the need for a water buyback to address the issue of over-allocated streams, but we see no sense in such a prolonged implementation phase," he said.

"Our communities simply will not survive if the government stays in the water market artificially inflating prices for a decade."

Federal Water Minister Penny Wong said yesterday the government would spend $3.1 billion purchasing water rights from irrigators as part of a 10-year $13 billion plan to rescue key water resources.

The government has also rejigged the Howard government's scheme to restore the Murray-Darling Basin by adding $1.5 billion in funding for urban water initiatives, including rebates for home rainwater tanks.

But Mr Whetstone said the buyback of water allocations needed to happen this year.

"The CSIRO will have all the necessary data to identify what streams are over-allocated and where the buyback will be most beneficial to the environment," he said.

"Let's get the buyback done quickly so that the Murray flows become sustainable again and we can get the stress out of our communities and the environment."

Mr Whetstone said over the past 12 months many irrigators had dipped into life savings and borrowed money to lease enough water to get them through in the hope their fortunes would change for the better.

Many of these people would not have the same finance options available to them next summer, let alone the next 10 years, he said.

"Despite being the most efficient irrigators in the Murray-Darling Basin, South Australian river communities are set to pay the heaviest price if this buyback process isn't shortened."--AAP