Government scientists will guide large-scale water diversion projects including dams under a re-elected coalition government.
The National Water Grid would be a new statutory authority planning and managing water infrastructure nationally.
Nationals leader Michael McCormack will make the election promise when the wombat trail makes a pit-stop in Canberra on Tuesday at the National Press Club.
"We know the key to unlocking the potential of regional Australian the answer is simple - just add water," he said.
The National Water Grid would employ scientists to find the best ways to harvest and harness water.
Their work would inform decisions about water infrastructure, in a bid to guard against political agendas.
Water is one of the most vexed policy areas affecting regional Australia, with the issue of buybacks returning to the spotlight during the election campaign.
The Nationals have been keen to promote dams and other infrastructure projects to support water security and agriculture.
Mr McCormack said the authority's first order of business would be to examine large-scale water diversion projects to deliver reliable and cost-effective water to farmers and regional communities.
The federal government would ask state and territory counterparts to co-invest in the body, while also giving them $100 million to kick-start their own water diversion projects.
The announcement comes one day after the coalition narrowed the gap in the latest Newspoll, though the government remains on track to get the boot.
Mr McCormack lavished praised on Prime Minister Scott Morrison's campaign efforts so far.
"He could be one of the great modern prime ministers, if he's given a chance," the Nationals leader told AAP.
Mr McCormack said feedback during his time campaigning in regional Australia had been positive, but he's not getting ahead of himself.
He's counting on Australians looking at the "big picture" when they cast their vote.
"Their incomes whether they're retired or they're working are reliant on the Liberal-Nationals government returning. Hopefully they'll vote accordingly," he said.
Mr McCormack campaigned in Mackay on Monday with Dawson MP George Christensen as pre-poll voting opened ahead of the May 18 election.
Australian Associated Press