An American water expert has warned of a looming water crisis in Perth if the city’s water use doesn’t drastically change.


Professor Robert Glennon, a water law professor from the University of Arizona, has warned that the quantity of water used by the city is propelling itself towards a water crisis.


Professor Glennon described the use of lawn space as an example of waste in the city’s water use.


"It's not functional, it's not being used for kids to play or anything," he said. "It's just sitting there looking green and taking water,” Professor Glennon told The West Australian.


"I expected a dry city on the driest continent would be at the cutting edge of water conservation and instead I'm hearing stories about groundwater wells in everyone's backyard and everyone has a lush lawn."


Professor Glennon has urged the Western Australian Government to learn from the mistakes of Southern US states in drawing too much groundwater, saying it should be particularly wary of drawing excessive amounts from the deeper parts of the city’s aquifers.


Professor Glennon said that drawing extensively from a single aquifer can have dire consequences for the entire subterranean ecosystem.


"The amount of rainfall has been decreasing in Perth for a couple of decades and the run-off and recharge into aquifers has also been decreasing, which means the amount of usable water is much less," Professor Glennon said.

"When you have declining surface water, substantial problems of over-pumping groundwater supplies and enormous costs associated with increasing supplies through desalinisation, it strikes me Perth is facing a major water problem."