The Average Public Swimming Pool Has About 20 Gallons Of Pee In It, Studies Show

The next time you're about to take a dip in a public swimming pool, here's a sobering thought to keep in mind --- there's roughly 20 gallons of pee mixed in there.

Swimming in a pool diluted with someone else's pee is a well-known risk of summertime, especially when public pools and little kids are involved. But scientific studies help point out exactly how much pee you might be risking swimming through when you dive into the water.

There have been a surprising number of studies done on the pee content in pools, and Live Science just compiled them all together to help answer the question once and for all. The most disturbing estimate comes from a study of Canadian pools conducted by the journal Environmental Science & Technology Letters. Researchers measured concentrations of the chemicals found in pee and found that a 220,000-gallon pool ---- which is about one-third the size of an Olympic pool, or roughly the size of a large public pool --- has about 20 gallons of pee mixed in.

While that may seem shocking, Live Science puts it in a bit more context.

"And yes, about 20 gallons of pee sounds gross — especially if you picture it as 20 milk jugs lined up in a row. But in a 220,000-gallon pool, that's only 0.01 percent of the total liquid in the pool — in other words, a drop in the bucket," the report noted.

The studies found that measuring pee in swimming pools is a bit difficult because pee contains many different chemicals, including some that are diluted and others already found in swimming pools. The studies took a variety of methods to attempt measuring the pee amount, but all found close to the same estimates.

Another study from the American Chemical Society found that there are about 1 to 3 ounces of pee per person in a pool, Live Science noted. That means roughly one gallon of pee for every 36 people in a pool at any time.
If that leaves you trying to do the math in your head the next time you take a stop at the public pool, know this --- there is most definitely already pee in there, and you'll be able to smell it. As the NPR noted, a study found that the "classic pool smell" often mistaken for chlorine is actually a chemical called trichloramine that is created when a chemical chlorine reacts with a mix of sweat, body oils, and urine.

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