All Australian states will be forced to use purified waste water for drinking if the current 100-year drought continues, said the Premier of Queensland state yesterday, after being the first to approve recycled water.

"I think in the end, because of the drought, all of Australia is going to end up drinking recycled purified water," said Peter Beattie, Premier of the tropical state of Queensland.

"These are ugly decisions, but you either drink water or you die. There's no choice. It's liquid gold, it's a matter of life and death," he told local radio.

Mr Beattie announced on Sunday that Australia's second largest state would become the first to use recycled water for drinking.

But the practice, which is used in Israel, Singapore, the United States and parts of Europe, does not have widespread public support in Australia.

To try to change opinions, Prime Minister John Howard and Environment Minister Malcolm Turnbull have backed Queensland's move.

"I am very strongly in favour of recycling and Mr Beattie is right and I agree with him completely," Mr Howard said yesterday.

Mr Turnbull said Australian cities, all now facing falling dam levels because of the worst drought on record, must incorporate recycled water in their water plans.

"Recycling is a real option for our cities," Mr Turnbull told reporters yesterday. "All of our big cities have to expand the range of water sources they have and include sources which are not dependent on rainfall," he said.

Australia's other five states and two territories have rejected the use of recycled drinking water, opting for desalination plants or tapping into underground water.

Mr Beattie had promised to hold a state-wide vote on the controversial issue of recycled drinking water but said the current drought had left him no choice but to authorise plans to start building water-recycling plants.

"I always indicated that if the drought continued... and we got to a position where we had no choice, we would do it anyway. We're at that no-choice position," he said.

Queensland Water Commission documents predict the state could start running out of drinking water in two years and could be dry by 2009, said Queensland's Courier Mail newspaper.

Mr Beattie said inflows into Queensland dams in December were 80 per cent lower than those in December 2004, the previously lowest levels. The dam system that supplies the state capital Brisbane was 20 per cent lower than previously lowest levels.

Mr Beattie said some residents would oppose drinking recycled water. The drought-hit Queensland town of Toowoomba, 140 kilometres west of Brisbane, voted against recycled water in 2006, despite a decade of tough water restrictions.

"We've made it clear that the water that we will put in will meet all health and safety requirements and will be probably better than what we're drinking now," he said.

Five facts on recycling sewage into drinking water

Here are five facts on how, where and why wastewater can be recycled.

• How is the wastewater recycled?

A combination of reverse osmosis and disinfection with ultraviolet radiation is the most common method. In reverse osmosis, water is forced through very fine membranes that filter out salts and other matter but let water molecules pass through.

• Who is already drinking it?

Singapore opened two NEWater sewage-recycling plants in February 2003. They add treated water to its reservoirs to provide about one per cent of the island's total daily water consumption.

Greater London does not formally add wastewater to its potable supply. But its 13 million residents joke their water has already been through five people before coming out of the tap, because towns upstream such as Oxford and Reading discharge their treated sewage into the River Thames.

• What's the benefit?

Wastewater has been recycled and used for watering parks and golf courses for decades. Using it to top-up drinking water supplies is seen as the next step to sustain the world's overstretched water supplies.

• Are there any down-sides?

As well as the psychological "yuck" factor of drinking former sewage, experts say such water purification projects use a lot of energy. There are also environmental issues about disposal of the concentrated salty waste water by-product.

• Better than the real thing?

Informal taste surveys have found most people can't tell the difference between tap, recycled and bottled water.

A 2001 University of Southern Florida study found the microbiological quality of water from a wastewater treatment plant was better than that from the local reservoir. (Reuters)

Sources: Australian Academy of Science (www.science.org.au); Public Utility Board, Singapore (www.pub.gov.sg); How Stuff Works (http://science.howstuffworks.com); Thames Water (www.thameswater.co.uk)