Prof. Collignon believes that the Australian Capital Territory government's plan to recycle treated sewage into Canberra's drinking water may pose a major health risk.

"One of the biggest advances in public health we've had, around the world, was keeping human sewage out of our water supply and the reason for that is that, obviously, waste contains a lot of bacteria, viruses, protozoans, including some we don't even know of yet that cause disease in people who then ingest that water," he said.

Prof. Collignon says that the ACT is fortunate in that it has one of the best sources of drinking water in the world. He questions the proposal to introduce recycled water to the territory, believing that the cost of such a proposal outweighed any potential benefit.

"What we've got in Canberra is, in fact, one of the best water supplies in Australia -from a safety point of view - because the catchment area is devoid of any human waste that gets in it and in fact even very little animal waste gets in it because there's so few farms that might be in the catchment area as well and for us to then take our sewage, treat it and pump it back into our water supply I think is a really bad idea... Why put that water there that has this potential risk when we've got other options... that are both cheaper and safer for us to do? ... I don't see that this proposal is going to do anything except increase our risk."

According to Prof. Collignon there are safer and cheaper alternatives - like better water management of the Cotter and Googong Dams.

"If there's actually something like maybe 35 gigalitres being released from those dams anyway surely we can increase that from 10 to 20 gigalitres and then we don't have a problem at all. We've still got very safe water in our dams and we don't have to go through this huge expense of maybe $100 to $200 million and we'll basically have a better health outcome or less of a health risk for our population."