PARIS • With the old “Toilet of Paris” freshly scrubbed for the Olympics, intrepid triathletes from the United States have been tasked to take the plunge and cleanse 100 years of sin from the Seine.

It’s a dirty job, but somebody’s gotta do it.

So rather than gripe and moan, American triathlete Seth Rider rolls up his sleeves, trots off to the bathroom every morning, and sits down to serious preparation for the risky business of taking a swim in the long-polluted river that runs through the heart of Paris.

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“We know there’s going to be some E. coli exposure,” Rider said Saturday, “so I try to increase my E. coli threshold by exposing myself to a bit of E.coli in day-to-day life.”

Say what?

How does a world-class athlete build tolerance for the bacteria lurking in the Seine, mistreated for decades as an open sewer?

“It’s actually a backed-by-science, proven method,” Rider insisted.

Are you ready to take a peek into the secret life of a world-class triathlete? Let me warn you: It’s kinda gross.

Might want to hold your nose.

And, please, don’t tell Mom.

“It’s just little things you do throughout your day,” Rider explained. “Like not washing your hands after you go to the bathroom.”

Well, nobody said training for the Olympics was easy. Or glamorous.

But I’m not too proud to admit Rider’s confession brought out the middle-schooler in me, causing me to snort like Beavis and Butt-Head.

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All potty jokes aside, though, E. coli is no laughing matter. The bacteria found in sewage and wastewater can result in stomach cramps, diarrhea and vomiting.

Maybe it’s a sad commentary on how we’ve messed with Mother Nature, but E. coli is more of a work hazard than you might think for professional triathletes as they live out suitcases and take the plunge in open waters around the world.

The city of Paris has gone to great pains, not to mention the enormous expense that translates to $1.5 billion U.S., in an effort to clean up the Seine. The triathlon is meant to be a victory lap, proof that humankind can reverse the damage of sins we’ve committed against the planet.

Despite threats last month by renegade environmentalists to make a big stink and poop upstream from Paris in protest, Mayor Anne Hidalgo donned a wetsuit and goggles to take a triumphant swim in the river on July 17.

“It’s sweet and wonderful,” declared Hidalgo, after emerging from the river.

Well, maybe not so much.

Test results released Friday showed bacteria levels were above the safe limits on the sunny day the mayor splish-splashed in the Seine.

Heavy rain, like the downpour that drenched the opening ceremony to the Summer Games, has been known to bump up the bacteria count in the Seine to levels unsafe for competition.

The Olympic triathlon events — which start with a 1,500-meter swim followed by a 25-mile bike race, then transition to the challenge of a 10k run to the finish line — are scheduled for the upcoming week. The men’s final is slated Tuesday, with female competitors set to gather on the banks of the Seine a day later.

“We’ve all been upping our probiotic uptake, which I think is the best way to assure that we have a strong gut and we can withstand any sort of sickness that might come our way,” said Taylor Spivey, a Californian whose parents are both accomplished veterans of Ironman competitions.

Wiggle room was built into the schedule to allow for at least one day for the bacteria in the river to abate, if necessary. But race organizers admit they could be forced to cancel the swimming portion of the race, which would be an embarrassment for Paris and reduce the Olympic triathlon into an awkward misnomer.

“Hopefully we get to swim, bike, and run because I don’t swim this much to just run and bike.” Spivey said.

The uncertainty is enough to make anyone a nervous eater and dive into a big bowl of ravioli.

“If you increase your carbohydrate intake, it lowers your chance of E. coli,” said Morgan Pearson, a University of Colorado alum who is ranked ninth in the world and has demonstrated the ability to be a legit medal contender.

With climate change a hot topic of intense debate around the globe, the International Olympic Committee has professed newfound interest in sustainability for future games. There’s been an earnest pledge to repeat the past mistake of expensive competition venues that can quickly fall into disrepair after the closing ceremonies and become a blight on host cities.

Perhaps no sport at the Summer Games embraces the great outdoors more than the triathlon. So maybe here’s where we begin to see if the Olympics really can help save the planet.

“We bike outside, we run outside and, when we race, we’re swimming in open water,” Spivey said. “Global warming and environmental conditions are a concern of ours.”

The triathlon in Paris is the Olympics’ first real attempt to kiss and make up with Mother Nature.