The Sound of Science - "Pee in the Pool"

Jul 27, 2018

Welcome to The Sound of Science on WNIJ.

(K) Today we’re going to tackle a question that we all try not to think about, but one that surely crosses everyone’s mind during the summer. Is there pee in the pool?

(P) Not what I want to talk about, but what about that chemical in pool water that changes color if someone pees in it?

(K) That is one persistent urban myth! There is no color changing chemical that indicates that someone peed in the pool.

(P) So, if that isn’t a real indicator, how do we know?

(K) Last year Canadian scientists came up with an ingenious way to study the amount of pee in a pool. They used an artificial sweetener called acesulfame-potassium (we’ll call it ACE for short) that is very resilient, it doesn’t decompose over time and our bodies cannot metabolize. ACE is found in a wide range of food products and its expelled from the human body solely in our urine. Because of how resilient and prevalent ACE is, the researchers in Canada decided it was a good chemical to estimate how much urine has been expelled into your average swimming pool. They tested pools for concentrations of ACE in two different cities. Using the concentrations found in the pools and the average concentration of ACE found in human’s urine the researchers calculated how much pee is found in public pools.

(P) Hopefully not much!

(K) Sorry to disappoint you, Pati. The researchers found that in a residential sized pool there would be about 2 gallons of pee. In larger, more used pools that number could go up significantly.

(P) Wow, that’s obviously gross, but is it dangerous?

(K) The urine itself isn’t dangerous; it's sterile. But chemicals in urine react with the chlorine in the pool and produce harmful chemicals. They can trigger asthma attacks and irritate the skin. But it is unlikely to hurt you in the long run.

(P) Well, what can swimmers do?

(K) Don’t pee in the pool! Tell you friends not to pee in the pool! And then compartmentalize; jump in and have fun.

(P) Keep your questions coming by emailing them to

(K) This is the Sound of Science on WNIJ, (P) where you learn something new every day.