Reports this morning indicate SA Premier Mike Rann has expanded his legal challenge against Victoria's 4pc cap on the volume of water being traded in any one year, to now include the 10pc cap on the amount of water that can be traded out of any single irrigation district in a year.

The move is sure to inflame tensions between the states ahead of tomorrow's Council of Australian Governments (COAG) meeting in Hobart.

The NFF wants that meeting to deliver on the Federal Government's Water for the Future plan, which includes a dedicated $5.8 billion rural water-use component.

The NFF is angry that after 18 months in office the plan is still "undelivered and the patience of farmers has been exhausted".

NFF Water Taskforce chair Laurie Arthur says if COAG again fails to agree on and fast-track the rollout of the on-farm component of the plan, "then the states must be bypassed on national water reform".

"The Federal Government's water reform agenda was sold to the rural sector on the premise that it is a two-pronged, co-ordinated approach for both water acquisition and infrastructure investment," Mr Arthur said.

"The Federal Government said it could deliver this plan due to the goodwill between it and its Labor State Government counterparts.

"Instead, the two-pronged plan has only seen one element, water acquisition, enacted on the ground.

"While it is important that the Government only buy water from willing sellers, farmers are still waiting for programs to fast-track water-saving works to off-set water buy-back and continue sustainable farm production."

Mr Arthur said that without on-farm infrastructure upgrades driving water savings, the water buy-back was "a half-baked solution".

"With water needed from on-farm water savings to restore environmental flows, state governments have simply failed to put projects together to meet these critical dual needs. Tomorrow is their last chance to act," he said.