THE state government has been investigating diverting water from coastal rivers to their drier inland counterparts.
The plans include a network of pipes that would send water from the headwaters of the Macleay River north of Armidale, to the start of the Namoi and eventually to Keepit Dam.
Another project involves sending water from the Barnard River, in to the Peel to fill up Chaffey Dam.
The projects have a combined price tag of more than $3 billion.
University of NSW water expert Stuart Khan said while it may sound like a "commonsense idea", the massive cost made the project impractical.
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"What you'll find with pumping coastal rivers inland, is that you've got to go across the Great Dividing Range," Professor Khan said.
"That requires a lot of pumping, which requires a lot of energy and money."
The cost of the projects would have to be passed on to water users, such as farmers, which would make the water vastly too expensive for them to use.
The project could be funded by taxpayers, however that could lead to unforeseen consequences.
"You'd have to think carefully about which irrigators benefit from this additional water at massively subsidised cost, while their competitors miss out," Professor Khan said.
"You'd basically be manipulating the market."
Professor Khan said the proposal was a "cheap and easy" opportunity for political point scoring, because politicians wouldn't mention the many barriers it faced.
"I'm cynical enough to say politicians see an opportunity to talk about something that will be well received in the community - the idea of taking water from where it is plentiful to where it is needed is commonsense," he said.
"But you'll notice nobody is going to put money on the table for this.
"If it was profitable, you'd have private investors lining up, but that's not the case."