SuggestedLeadIn: Athletes competing in an Olympic test event at Rio de Janeiro's Guanabara Bay have raised concerns about the water quality despite the Brazilian Government's extensive treatment program.

Script: This is Guanabara Bay in Rio de Janeiro.

It's one of three Olympic water venues in the spotlight since a report by The Associated Press revealed dangerously high levels of disease-causing viruses from human sewage.

Spain's Iker Martinez is a member of what's considered "The World's greatest duo" by the International Sailing Federation,

SOUNDBITE (Spanish) Iker Martinez, Athens'04 Gold Medallist and Beijing'08 Silver Medallist from Spain

"I saw people who became ill, but I don't know if it is because of the water, or the food, or jet lag. I am not an expert on that and I can't make an assessment. Personally, I would like to have it (Guanabara bay) cleaner."

A week-long International Sailing regatta has just started at the venue, despite serious concerns about the pollution.

American Olympic sailor Sarah Newberry.

SOUNDBITE Sarah Newberry, Nacra 17 sailor from the United States.

"It's been good. We actually haven't had any issues. At all. Not in three trips. (Q: Any worries about, you know, some of the report that come out with the quality of the water?) No. Uh… We feel like we have done everything we can do to prepare to sail here and we're still going to wind up doing our job well."

The Brazilian government has spent $US3 billion over the past 20 years treating the bay.

They now have less than a year to make it safe for athletes.