Water saving, recycling and desalination might be better ideas than building dams as NSW grapples with what might be the new normal - less rainfall due to climate change.

That's according to ANU Crawford School honorary professor John Williams, responding to NSW Deputy Premier John Barilaro's call to build more dams so towns don't run out of water in the future.

Professor Williams says there are empty dams everywhere in NSW, and it has to rain to refill dams, aquifers and groundwater.

He tells Michael Condon that while he is not against dams, "you have to look at the whole system and [make sure] that you don't end up paying Peter and robbing Paul".