The State Government has announced recycled waste water will become Perth's next source of drinking water.

The government plans to roll out its groundwater replenishment scheme, which has been trialled in a water recycling plant for the past three years.

Under the scheme, household and industrial waste-water that would normally be pumped out to sea, is instead filtered and disinfected before being pumped hundreds of metres underground into aquifers.

The treated water then mixes with groundwater, undergoing natural filtration for up to three decades before extraction.

The Water Minister Terry Redman says the water is pure after the treatment process, but putting it in the aquifers for naturalisation means by the time the water is extracted, it will be the same as the groundwater in the aquifer.

Mr Redman says he is confident the community will support the scheme.

"I think it is appealing to the public when you look at the fact we live in a drying climate, our population is growing, our water levels and the inflows to our dams are decreasing, we need to be securing and sourcing climate independent sources of water," he said.

Mr Redman says the scheme will initially supply seven billion litres of water every year and has the potential to supply up to 20 per cent of Perth's drinking water needs.

He also says treating waste water is cheaper than a desalination plant and uses about half the energy.

Concerns

The State Opposition has welcomed the plan, but says they have concerns about the level of public consultation.

Labor's Water Spokesman Dave Kelly says he is worried the Government will not listen to people's concerns.

"The Government has an obligation to get out there and educate the public and win over the public, to this idea, rather than just doing it," he said.

"The Government are the custodians, if you like, of the confidence that we have in the drinking water that comes out of our tap."