Water quality is a health concern in all public pools, and although it won’t turn the water green, urine can pose hazards to swimmers’ health. Unfortunately, it’s difficult to detect in the chlorinated water of a huge pool.

So how do you measure pee? Test for sweetness, University of Alberta chemists propose in research published this spring in the journal Environmental Science & Technology Letters.

Using an artificial sweetener as a proxy, they discovered that all of the 31 public pools and hot tubs they tested contained urine.

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