Is there a chemical in swimming pools that reveals urine? Fact Check

A long running legend claims that certain swimming pools utilise an invisible dye or chemical that turns a bright color when it comes into contact with urine, thus allowing pool staff to see who pees in the pool.

Passed on from parent to child, the legend of the urine-revealing chemical lurking in public swimming pools is today still widely believed and accepted, despite being around for decades and being completely false.

So popular in the myth, that those in the industry often report to be frequently confronted with requests for “urine-indicator dye” or “that wee revealing chemical” as it has come to be known. In fact the National Swimming Pool Foundation dubbed the legend to be the “the most common pool myth of all time”

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Despite the legend most likely first appearing to deter young children from stealthily taking a pee while in the swimming pool, so believable is the story, that even adults have taken the claim as face value. A survey revealed that around 50% of Americans had believed it.

One can even purchase fake signs purporting of “urine detectors” in a swimming pool.

Experts claim that such a substance or chemical could theoretically be produced to detect urine in swimming pools and change color as a result. However the challenge, they say, would be to limit the reaction to urine only, and not produce unwanted and embarrassing “false positives” when it comes into contact with similar human excretions such as sweat or dirt.

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And, of course, there is the argument that for many a child, the prospect of producing brightly coloured, flowing clouds of chemical dye may be too good an opportunity to pass up, consequently having the opposite effect than intended.

As such, we’re unaware of any public swimming pool using such a substance, meaning for now this remains both an urban legend believed by adults as well as a tale passed on from parents to their children.