There's still lots and lots of faeces in the water at the Rio Olympics

Peter Burling and Blair Tuke celebrate on the podium after winning silver in the 49er sailing class at the London 2012 Olympic Games. Photo / Getty Images

Athletes taking part in water-based events at the Rio Olympics will have to deal with a lot more than fierce competition; they'll also have to deal with the fierce sludge of human waste because a lot of sewage is still being dumped into the city's waterways, and especially Guanabara Bay, USA Today reports.

"A giant pipe running from downtown churns human waste into the marina [on Guanabara Bay] at certain times each day. Rats roam around in the waste. The stench makes uninitiated visitors feel like vomiting or fainting," USA Today's Martin Rogers reported on Tuesday, less than two weeks before the Games kick off on August 5.

The waters not quite being up to snuff (and sniff) isn't exactly a surprise. Last year, Rio Mayor Eduardo Paes conceded the city's original plan to rid the waters of pollution wasn't going to be met.

"I think it's a shame," Paes told Brazil's SporTV last March about the city's inability to make the waters clean. "I think it's a lost opportunity."

Rio resident Luiz Goldfeld, who lives in a houseboat on the bay, agrees.

"What an opportunity," Goldfeld told USA Today. "There was a chance to make this place wonderful again, but they have wasted it. There was too much corruption and no political will to get it done."

The city's politicians and Olympic organisers started in 2009 with a lofty goal in its bid for the Games. They pledged to remove and treat 80 per cent of the sewage in the waterways by 2016. Although that hasn't been met, some improvements have been made, according to officials.

"The situation has improved compared to what it was before, with the barriers and the boats and the pipes around Guanabara Bay," Christophe Dubi, the International Olympic Committee's executive director of the Olympic Games, told ESPN's Outside the Lines this year. "It's become very challenging from an economic standpoint, so what [Rio has] done already at this stage is much improved from what the conditions were at the time [the city won the bid]. It's not 80 per cent, but it has improved since 2009."

The bay just being gross-looking and smelling isn't what's worrying athletes the most, however. They're also concerned about viruses and bacteria in the water that can make them sick.

Kiwi 49er Blair Tuke said he and teamate Peter Burling are prepared for Rio's polluted waters, telling One News' Martin Tasker "it's not Auckland Harbour".

"It's not clean but it is what it is and we've got things in place to try and deal with that," Tuke said.

An AP investigation last December found in the water high counts of active and infectious human adenoviruses, which can give people mild to serious symptoms.

"These are viruses that are known to cause respiratory and digestive illnesses, including explosive diarrhea and vomiting, but can also lead to more serious heart, brain and other diseases," AP's report (via Huffington Post) stated.

Despite the danger, the allure of Olympic glory means some athletes are still willing to take their chances.

"From everything I understand, the worst that can happen with the race is that a couple of days later, I might get a little sick," US triathlete Sarah True told Outside the Lines. "In the very large scheme of things, that's a risk I'm willing to take. I'm far more concerned for the people who live there, who were made these grand promises to improve their environment. For those promises not to be delivered on is appalling to me."