Canadian researchers have delved into an age-old question most of us would rather not think about — just how much pee is in a public swimming pool or hot tub at any given time?
(If you really value your hygiene and don't want to know the answer, click away now. Seriously.)
University of Alberta environmental toxicology expert Xing-Fang Li worked with a team of researchers to determine that the "sweetness" of a pool is a good way to determine the concentration of urine.
The test measured the concentration of an artificial sweetener, acesulfame potassium (ACE), that is common in the human diet and passes through the body unaltered.
ACE is often found in processed foods like baked goods, sodas and other sweetened items.
Of the 31 pools and hot tubs the team tested between May and August of 2014, every single one of them tested positive for ACE.
What's even more disgusting is they found that a pool about one-third the size of an Olympic pool (830,000-litres or 220,000-gallons) had 75 litres of urine. Another smaller pool had 30 litres.
The concentration of ACE was 570 times greater than what occurs in normal tap water.
The locations of the pools and hot tubs tested were not revealed, although the study says the tests took place in two Canadian cities.
And while it's gross to think about, we know what you're thinking: maybe it's OK because urine is considered sterile and wouldn't the chlorine kill anything harmful, anyway?
The study says urine can mix with other pool chemicals and cause disinfection byproducts, which in turn can cause eye irritation and respiratory problems.