Like many, Bob McCormack was shocked in late July when he read reports of high viral levels of sewage contamination in all the Olympic water venues in Rio de Janeiro, Brazil, site of next year's Summer Games.

Pictures of dead fish, plastic bags and chocolate milk cartons floating around did little to alleviate his concerns, but two trips to Rio over the last four months has Team Canada's chief medical officer for the 2016 Games believing "steady progress" is being made by Olympic officials.

"After learning the background story I feel much better and reassured that the risks [of athletes getting sick] will never be zero, but it's not the levels of concern that were expressed in some of those [Associated Press] reports," McCormack, who visited Rio last week, told CBCSports.ca in Toronto on Wednesday.

'To suddenly put in the infrastructure for a Canadian-type sewage system, it's not going to happen in eight months. I've talked to rowers and a few kayakers and their concern is ... debris in the water and cross winds.' - Bob McCormack, Canada's chief medical officer for Rio Olympics

McCormack, a professor in the faculty of medicine at the University of British Columbia and an orthopedic surgeon, has viewed data from the extensive testing of the water being conducted on a regular basis.

While he didn't dispute reports that 50 per cent of the sewage in the metropolitan area of Rio goes untreated, McCormack understands officials are working to make sure the water quality at the athlete venues is acceptable.

"To suddenly put in the infrastructure for a Canadian-type sewage system, it's not going to happen in eight months," he said. "I've talked to the rowers and a few kayakers and their concern is not so much water quality but debris in the water and the crosswinds."

In all of the water-based test events held in Rio, McCormack said, no Canadians have become ill and only six per cent of international athletes.

McCormack noted Canadian athletes are better educated about the risks and how to minimize their chances of getting sick when travelling internationally and competing in developing countries.

Issues in lagoon

His trip to Rio a week ago didn't end without some concern with the water. The Rodrigo de Freitas lagoon, where rowing and canoeing will be contested, has issues at the bottom of the basin.

"If there's a heavy rainfall, everything gets washed off land [into the water] like here [in Canada] if it was to rain after a long dry spell and the oil comes to the top of the road," said McCormack, the CMO for Team Canada since 1976. "We have to have contingency plans for something like that. Generally, the water has been not bad."

'A couple of antibiotics a couple of days out and then I drank a can of [pop] after the [test] race and had no issues. I'm not worried about the water quality at all.' - Canadian long-distance swimmer Richard Weinberger

The highest place of risk, he said, is the Copacabana beach, site of the triathlon and marathon (10-kilometre) swim events, where the athlete's head is below the water for an extended period. But, as McCormack pointed out, the water quality in 2014 was better than the international acceptance standards 100 per cent of the time, and 97 per cent of the time this year.

On Wednesday, Canadian long-distance swimmer Richard Weinberger told Scott Russell of CBC Sports he took the necessary precautions prior to competing in a test event in Rio.

"A couple of antibiotics a couple of days out and then drank a can of [pop] after the race and had no issues," said Weinberger, a bronze medallist in the open-water swim at the 2012 London Olympics.

"I'm not worried about the water quality at all."

However, there is some worry with sewage entering some areas of Guanabara Bay, site of the sailing and aquatic events. But officials have been taking measures to divert that sewage and improve the infrastructure in the highest-risk areas.

"I wouldn't drink the water out of the [lagoon]. No one should," said McCormack. "That's different than the risk of being on top of the water and getting splashed."