Speaking at Canberra's Parliament House following a meeting of state and territory water ministers, federal water minister Ms Plibersek said the Commonwealth remained committed to delivering the legislated plan.

"What's not up for negotiation is our full delivery of the Murray-Darling Basin Plan," Ms Plibersek said.

"We absolutely have to get there … I'm flexible about how we get there, but we will have to get there."

However, Ms Plibersek would not say if she now expects the plan to be completed by its June 2024 deadline.

"I'm pushing for 2024 implementation, but I'm acknowledging that it's hard to get there … we need a pathway to get getting to the full implementation of the Murray-Darling Basin Plan.

"I have to take into account, realistically, what states and territories are saying to me, but I'm not taking my foot off the accelerator just yet.

"We've got a work program between now and the next Minister's Council, which will be early next year, which will flesh out how we intend to deliver on those [water-saving] targets, but deliver we must."

The ministers are now expected to meet in February when a decision on extending the basin plan could be negotiated.

A communique released following the meeting said the minsters would also consider strategic water buybacks.

"As a matter of priority, the Commonwealth will work with relevant communities and basin states on options to bridge the remaining gap in water recovery, including through strategic purchase, and to consider carefully opportunities to achieve the 450 gigalitres [environment water target]," the communique said.

As minister, Ms Plibersek has so far avoided making a commitment to introduce water buybacks, which have been opposed by Victoria and New South Wales.

"I have to say, I see that voluntary buybacks in a strategic way can be very beneficial," Ms Plibersek said on Wednesday.

Hundreds of gigalitres unrecovered

With less than two years until water savings must be reconciled, hundreds of gigalitres are yet to be recovered for the environment as set out in the plan.

Victoria and New South Wales have repeatedly, and so far unsuccessfully, pushed for deadline extensions.

South Australia used Wednesday's meeting to request federal funding for on-farm water-saving projects and Commonwealth water buybacks to meet the water-saving targets.

Buybacks haven't happened in Australia for almost a decade and, like on-farm water-saving projects, were opposed by the former federal Coalition government.

The Murray-Darling Basin Plan sets out how water in Australia's largest river system is shared between farmers, communities and the environment.

Since it was legislated a decade ago, more than 2,100 gigalitres has been reallocated from farming to the rivers, mostly through buybacks.

In recent years, a series of independent reports have found that a commitment to deliver an extra 450 gigalitres of water back to the environment is unlikely to be met.

With just 2 gigalitres of water recovered so far towards the 450-gigalitre target set in 2018, federal Labor made a pre-election commitment to deliver the water.

The agreement that was struck in 2018 by water ministers set out strict criteria by which the water could be recovered, ensuring no negative community impacts.

This week, South Australia withdrew its support for that criteria.

It is unclear what that means for other jurisdictions in the basin, or if such a move could jeopardise Commonwealth funding for basin projects in that state.

Speaking after the water ministers' meeting, SA water minister Susan Close said delivering the 450 gigalitres for the environment was necessary for a sustainable basin.

"[There's a] long way still to go, particularly from South Australia's perspective — with our very deep concern about the lack of recovering of the 450 gigalitres for the environmental health of the basin — but, nonetheless, it was the tone of cooperation and an attitude that said: 'We are prepared to get this plan done'."

For years, New South Wales has lagged behind on commitments required under the Murray-Darling Basin Plan, including completing water resource plans and administering major water-saving projects.

New South Wales water minister Kevin Anderson used the ministers' meeting to once again call for an extension to the plan.

"During today's meeting, I called on basin state ministers to agree that greater flexibility is needed to deliver the outcomes intended under the plan," he said afterwards.

"I am pleased that ministers supported my recommendation that a clear plan will be needed to be developed, with specific actions that will provide flexibility for delivering projects and dealing with shortfall towards basin plan targets."

Mr Anderson said this would ensure delivering the basin plan would not come at the expense of communities that live and work in the basin.

He also said that New South Wales was committed to completing all of its water resource plans by the end of 2022.

Victoria's water minister, Harriet Shing, said her state also remained committed to delivering the basin plan.

"Basin governments have worked together for 10 years to deliver this plan without socio-economic harm and it's important we continue to give Victorian communities the security they need to continue delivering the basin plan," Ms Shing said.

First Nations and water trading

Ms Plibersek promised that this month's federal budget would include $40 million for First Nations Australians to participate in the water market.

The funding was first promised by the Coalition in 2018 and has yet to be delivered.

"That $40 million has never been in doubt. It's 100 per cent going to be there," Ms Plibersek said.

The water ministers also agreed to adopt 23 independent recommendations about how to regulate Australia's water market.