Now Science Knows Just How Much Pee Is in a Public Pool

When you take the family to visit a public pool, you’re probably worried about the urine content of the pool, right?

What? You weren’t?

Well, you’re probably about to be. Luckily for you, science was worried, so they decided to figure it out for some reason. And, like a lot of science, the answer is more than a little disturbing. From Ars Technica:

As Ars has reported before, those disturbing warm spots create harmful chemicals. Urine and chlorinated water react to form trichloramine and cyanogen chloride. At certain doses, these can cause respiratory and eye irritation. At high doses, cyanogen chloride can kill—it’s considered a chemical warfare agent. The levels found in pools, however, are nearly negligible. Long-term exposure by professional swimmers and pool workers may be linked to asthma, but otherwise it’s unlikely to cause many problems. And as Ars has also reported, you’d need a hellish scenario of two-parts water, one-part chlorine, and the wee of three million people in a pool to get to a lethal situation.

Still, it’s hard not to be curious about how much pee we let slip while taking a dip—and now we have the answer.

By analyzing pool water for a sweetener commonly found in human urine, Canadian researchers estimated that there were about 75 liters of pee in a large public pool—which contains about 833,000 liters or is a third of an Olympic pool. That’s about half a bathtub’s worth of pee. In a pool half the size of the first, the researchers reported an estimated 30 liters of pee. Their study was published Wednesday in Environmental Science & Technology Letters.

Now I’m not sure what’s more disturbing, the urine content of swimming pools or the fact that someone figured out there was a “sweetener” in urine. Seriously, why is that there? I refuse to ask just how someone figured out it was a sweetener. I’m sure there’s some boring, safe explanation, but there might not be, and thus we discover the limit to my curiosity.

OK, there actually is a boring explanation in the article, thankfully. The sweetener is an artificial one in a lot of processed foods we eat, which is then transported into our urine.


Anyway, scientists tracked this sweetener to give them an idea of just how much urine was in the pools. What they found was the sweetener existed in pools at concentrations 570 times greater than tap water. Of course, one would assume that there are no sweeteners in tap water, so…

It seems that the urine in pools is rather accumulative, however. After all, most places don’t refill their pools regularly, they just add water because it’s cheaper. That means the urine only evaporates as a percentage of the whole pool, so everytime someone creates a warm spot in the cool water, it adds more and more.

While the overall percentage of urine is low (less than .01 percent), it’s still more than most folks will want to wallow around in. It’s just too bad no one told us this at the beginning of summer!


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