SOUTH Australian Premier Mike Rann has been accused of hypocrisy in launching High Court action last week to lift Victoria's 4 per cent cap on water traded out of gravity irrigation districts.

Victorian Farmers Federation water council chairman Richard Anderson said Mr Rann signed the interstate National Water Initiative in June 2004, in which he and other Premiers agreed to review the cap in 2009 with the aim of phasing it out completely by 2014.

"Yet here he is taking High Court action to remove the cap," Mr Anderson said.

"If you sign a contract, you don't start suing until you get to the allocated date and nothing has happened."

But a spokeswoman for Mr Rann said the South Australian Premier had always disagreed with the NWI clause on delaying the full removal of the cap until 2014.

"The Premier made his disagreement known at the time, but agreed to (sign) it to get the process going," Mr Rann's spokeswoman said.

"If we had got stuck on that one issue, we would have never got the whole NWI agreement signed."

Mr Anderson said it seemed Mr Rann's backflip had more to do with the March South Australian state election than anything else.

"That's the hypocrisy of politics for you," Mr Anderson said.

The VFF has long argued the seasonal 4 per cent cap on water entitlement traded out of the state's gravity irrigation districts must be retained to slow the impact of losing water on Goulburn Murray irrigation communities.

But not all VFF members support retaining the cap.

The VFF's Sunraysia branch has voted in favour of removing the 4 per cent cap, which puts it at odds with the VFF and Victorian Government.

Sunraysia branch president John Piccirillo said ongoing low allocations and the government's refusal to qualify rights for permanent plantings had forced the branch to call for the removal of the cap.

In launching the legal challenge last week, Mr Rann said the cap was an unconstitutional imposition on trade and is therefore invalid.

"It is a mechanism to protect inefficient and wasteful water practices in Victoria," Mr Rann said.

Victorian Water Minister Tim Holding lashed out at Mr Rann's claim saying it was an insult to every Victorian irrigator.

"The 4 per cent cap exists to protect vulnerable, drought-stricken communities from being destroyed by huge volumes of water being traded out of their area quickly," Mr Holding said.

"What Mike Rann's political stunt fails to recognise is that Victoria has already reached an agreement with the Commonwealth to suspend the cap where necessary to enable more water to flow to the environment.

"I think all Australians are getting sick and tired of the South Australian Government's faux outrage on these issues."