Leading water experts have urged the Federal Government to tackle the country's water shortages at next week's Council of Australian Governments (COAG) meeting.

A briefing in Melbourne has been told water reform has been talked about on a federal level for 14 years, but there has been no action.

Professor Mike Young, of Adelaide University, says it is crucial COAG acts on water trading.

He says any new system for the Murray-Darling Basin should include shares for all states and a separate allocation for the environment.

Peter Cosier, of the Wentworth Group of Concerned Scientists, says the Federal Government needs to accelerate the buy-back of water rights and provide investment packages to help rural communities readjust.

"Unless it buckets down with rain in the next few weeks, come next summer we're going to confront an environmental and human catastrophe the like that which we have not seen or even imagined possible 20 years ago," he said.

"The Coorong, in the lower lakes, we're seeing some of those lakes turn acid," he said.