How much urine does your local swimming pool contain?

Sneaky swimmers add around 75 litres of urine to their local swimming pool every two weeks, according to a new study.

The eye-opening findings come from Canadian researchers, who monitored two public pools for a fortnight to see just how often swimmers were indulging in the ultimate pool taboo.

Scientists from the University of Alberta tested water samples for acesulfame potassium (ACE), an artificial sweetener found in many processed foods that passes into urine, unaltered and can thus be easily detected.

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One pool, which was one-third the size of an Olympic pool, accumulated 75 litres of urine over two weeks – "enough to fill a medium-sized dustbin", says The Guardian. A smaller pool was found to contain around 30 litres of urine.

The good news for squeamish swimmers, however, is that urine still made up less than 0.01 per cent of the water.

Chemist Xing-Fang Li's team also tested hot tubs and found evidence that even more people were relieving themselves in the jacuzzi. The most contaminated hot tub showed more than three times the concentration of ACE than the worst swimming pool.

"Apart from being gross, that's also a potential health hazard," NPR reports. Urine and sweat react with the chlorine used to purify pool water, creating the distinctive "pool smell". The reaction also creates nitrosamines, a chemical compound linked to cancer, although there is currently not enough evidence to make a definitive link between swimming in public pools and an increased cancer risk.

Li told NPR that he himself is a keen swimmer. He hopes the study will encourage better hygiene practices rather than put people off the pool.

"This isn't to scare people, but hopefully they can prevent the problem," said Li. The chemist is urging swimmers to shower before entering the water and to get out of the pool to answer nature's call.

In a 2012 survey cited by the Guardian, 19 per cent of adults anonymously admitted to urinating in a swimming pool on at least one occasion.