Western Australian Nationals leader Brendon Grylls has defended the state’s decision to pump recycled water into one of Perth’s main water sources, the Gnangara Mound aquifer.


Mr. Grylls urged people to “get over it” when faced with drinking recycled water, saying that it was the only way to avoid water shortages as the state faces drying dams.


"We've got a major challenge in providing water for the future and there could be two choices: recycled water or buy it in a bottle and tip it into the bath." Mr Grylls said.


"It's a bit like the carbon tax. A lot of the facts are washed away and a lot of the rhetoric becomes what people understand.


"Direct recycled water into the grid is probably tricky [to convince the public to support] but water reinjected into the aquifer, shandied with existing ground water sources, filtered through the same sand-water filter that many of you have on your pool filter at home would be a step that I think the community is willing to take” Mr Grylls added.


Mr. Gryll’s urgings come as the Centre for Water Research found that Perth’s water supplies from its dams are at risk of running out within the next six months regardless of a solid amount of rainfall.


The plan has also attracted criticism from US scientist Steven Oppenheimer, director of cancer and development biology at California State Northbridge University, who has likened the plans to "playing Russian roulette" with public safety.


Professor Oppenheimer said "toilet-to-tap" water posed an inherent public health risk and should be used only as a last resort. 


Australian National University microbiologist Peter Collignon has also said that current testing standards in Australia could not account for all the potential harmful agents in sewage.


He cited a National Water Commission report, released this week, to argue there were shortfalls in the arrangements safeguarding public water supplies.


The report warned of "emerging contaminants" in alternative supplies, including recycled effluent but found "there are outward signs that the broader regulation of urban water quality in Australia is not equivalent to best practice".


"To me, the fundamental issue is you only do it if you really don't have any other viable option, which for most areas of Australia is not true," Professor Collignon said.


"But if you do (have to) do it because you don't have any other choices, then I think it's really important that you do lots of tests, including those for viruses and in general they are not done very well very often."


He said there were too many unknown chemicals and pathogens for the process to be foolproof.