But a study was just done by researchers at the University of Alberta in Canada to determine the amount of tinkle in the average public swimming pool, and the results aren't pretty. While there were trace amounts of artificial sweeteners in the tap water itself, the amount was 570 times higher in the pool water, confirming that people had been secretly peeing in public. Based on those concentrations, they concluded that a 220,000-gallon commercial-size swimming pool likely contains nearly 20 gallons of urine.
The sweetener can be found in varying concentrations in natural waterways and tap water, but no one had checked for it in public pools before the team chose to take the plunge.
This was done by identifying the synthetic sweetener acesulfame-K (ACE) - which is widely consumed - and examining its excretion in urine.
In another pool that was half as big, about 26.5 litres of urine was estimated in the water.
And once you've peed in a pool, the urine is likely there to stay.
About one in five Americans admit they've peed in the pool. It zips right through our bodies, and researchers knew its average concentration in urine.
When mixed with chlorine in a pool or hot tub, urine can contribute to the formation of so-called "disinfection by-products" in pool water that can be harmful to a swimmer's health.More news: USA to Award Contracts for Building Mexico Border Wall
Blackstock explained to ResearchGate that urine, like sweat, is a main contributor of nitrogenous compounds in pools and tubs.
The locations of the pools and hot tubs tested were not revealed, although the study says the tests took place in two Canadian cities.
When ACE levels were measured, the research team found that in a three-week period, people put in at least 7.92 gallons of urine in the smaller pool, and close to 20 gallons into the bigger one.
Exposure to these chemicals can lead to eye and respiratory irritation and has been linked to some types of asthma. Their work has been published in Environmental Science & Technology Letters.
"However, we do have many compounds in urine, for example urea and nitrogen-content compounds, which can react with chlorine disinfectants that can produce by-products we don't want to be exposed to."