Groundwater that supplies Perth is drying up. 

A major problem is threatening the city's vital non-drinking water supplies and groundwater-reliant ecosystems.

The WA Government is looking at a cut of 19 per cent to water allocations, but experts say water reuse options are needed too. 

Data from the state’s Department of Water and Environment Regulation (DWER) shows that water levels in some areas are stable, but others are rising due to urbanisation, with many in decline.

The DWER says a combination of climate change and water abstraction has led to the loss of 1,000 gigalitres of groundwater from one of Perth's threel aquifers since 1980.

The state government has put forth the Gnangara Groundwater Allocation Plan, which would see home bore users have their sprinkler days reduced from three to two per week.

It also includes plans for the allocations for licence holders, such as local governments and industry, to be reduced by 10 per cent. The Water Corporation's abstraction would be reduced by 27 per cent.

WA Minister for Water Dave Kelly says the cuts are needed to maintain Perth's green spaces and minimise its urban heat island.

“If our groundwater continues to decline, it's our wetlands, our parks and our street trees that are going to suffer the most,” he has told reporters.

“I know some people won't be happy about [the plan] but by and large people understand the days of using our water, without regard to it being precious, have really changed.”

But some experts say the plans rely too heavily on pumping reductions.

They say the state should look at reusing some of the hundreds of billions of litres of water that is pumped from wastewater treatment plants and drained from urban areas every year.

The Water Minister says the government has considered reuse options, but these come with significant costs.

“Asking water users to be more efficient with the water we already have is the cheapest way we can save water,” he said.

“We are looking at local options to assist our wetlands, all those possibilities are there.

“But you can't simply go to the most expensive option, because of the cost to the taxpayer which is ultimately reflected in people's bills.”