The amount of urine in a swimming pool will shock you

What could be more pleasant than a dip in the pool after a long day? To relax in cool, clear water? Well, fresh and clear, yes, but clean is another story. This was the finding of a study conducted by Canadian researchers and published in the journal Environmental Science & Technology Letters.

Scientists from the University of Alberta succeeded in developing a test capable of estimating the quantity of urine released into a large volume of water. The test is based on the detection of acesulfame potassium (ACE). This artificial sweetener is one of the most widely used in the food industry and has the particularity of being extremely stable. Lindsay Blackstock, PhD student and lead author of the study explained:

We don't metabolise [these sweeteners], so they pass through our bodies and are not completely broken down

Eliminated via urine, CEA is thus 'an ideal urinary marker'. By measuring its concentration, it is possible to assess the quantity of urine contained in water.

Up to 75 litres of urine

This is what the scientists did after taking 250 samples from around 30 swimming pools and hot tubs in two Canadian cities. They also tested two public pools for three weeks. And the results are as revealing as they are frightening.

The sweetener was identified in all the pools and hot tubs tested. In one pool, with a volume of 830,000 litres (one-third of an Olympic-sized pool), the tests revealed a volume of 75 litres of urine. In the second, half the size, 30 litres of urine were detected. The concentration of CEA was even 570 times higher than in drinking water samples.

Although two pools were tested over a period of three weeks, the scientistsdid not record the number of visitors. It is therefore difficult to say how many people urinated in the pool each day. But Lindsay Blackstock commented:

Our study provides further evidence that people do urinate in public pools

Promoting hygiene

As reported by The Guardian, the doctoral student continued:

We want to use this study to promote public education about proper bathing hygiene practices. We should all be considerate of others and make sure we get out of the pool and use the toilet when we need to.

This is not the first time that a study has denounced swimming pool hygiene. However this problem, and in particular the presence of urine in water, is far from being without consequences.

As the researchers pointed out, certain compounds in urine such as urea and ammonia tend to react with swimming pool disinfectants. Reactions that form by-products known to be irritating to the eyes and lungs, such as trichloramine. These are also responsible for the infamous red eyes at the pool.

This article was translated from Gentside FR.

Read more:

⋙ Beware! Public swimming pools are dirtier than you think

⋙ Swimming right after eating is actually not as harmful as you thought

⋙ Is it safe to go swimming while on your period?