Labor wants to remove a cap on the amount of water the Government can buy from irrigators in the Murray-Darling Basin.

“After the summer we've had, you'd have to say there is some possibility that at some point the Murray-Darling Basin Authority conducts its own reviews as it does under law, may well decide that more water has to be returned to the system to health than was previously recommended,” Labor's water spokesperson Tony Burke said this week.

“By removing the cap we are making clear that if we end up having to provide more water for the rivers then this will not be a barrier to doing this.”

The new policy will be introduced in a private member's bill before the Senate this week.

The cap of 1,500 gigalitres was set in 2015.

“This cap was set at a level which provided some assurance for those communities during the early years of the plan,” Mr Burke said.

“But it does not make sense to keep it there as a permanent level because ultimately it will come up against the flexibility that the Authority needs and what it might recommend.”

South Australian Liberal Senator Anne Ruston said removing the cap would be a “lazy” solution.

“As of today, 270 billion litres of water is still available through the cap buyback, we haven't even reached the cap of 1,500GL,” Ms Ruston said.

Ms Ruston said removing the cap would create uncertainty in river communities.

The National Irrigators' Council is disappointed, with chief executive Steve Whan saying, “it's not necessary”.

“There's still room under the cap,” Mr Whan said.

“It seems to be a breaking down of the bipartisanship, which is vital to the success of the plan.”

Meanwhile, reports say the Greens will soon introduce legislation to establish a federal Royal Commission into the Murray-Darling Basin.