CANBERRA, March 19 (Xinhua) -- A major population boom will leave most Australians relying on recycled sewage water for drinking, experts have said.

Adam Lovell, executive director of the Water Services Association of Australia, said that residents of at least one state capital city will be relying on recycled water "in the next decade."

Projections have revealed that at the current growth rate, Australia's population will surpass 40 million people within the next 40 years with Melbourne overtaking Sydney as the country's largest city.

"For Australia to really grow and to have competitive cities and liveable cities, we have to embrace potable reuse as one of our supplies going forward," Lovell told the Australian Broadcasting Corporation (ABC) on Monday.

He said that for smaller inland cities where desalination is not an option, drinking recycled water could happen even sooner.

Warragamba dam, the storage facility that supplies Sydney with its water, currently has the capacity to store four years' worth of water for the city.

However, when the population has doubled in 50 years it will fall to two years and even that relies on high rainfall to keep the dam full.

Lovell said that even desalination plants were being rendered obsolete because a vast majority of population growth in major coastal cities was occurring away from the coast.

"Water being non-compressible and quite a heavy substance -- it's quite expensive to transport," he said.

"Even if you're looking at Sydney on the coast through to Penrith or from Wonthaggi to the north of Melbourne, you're looking at 80 to 90 km. That's really expensive, and it's a really inefficient way to transport water."