Urine-indicator dye is a substance which is supposed to be able to react with urine to form a colored cloud in a swimming pool, thus indicating the location of people who are urinating while they are in the pool. A 2015 report from the National Swimming Pool Foundation called this ''the most common pool myth of all time'', with nearly half of Americans surveyed by researchers believing that the dye existed.

Is it true that will pool water turn blue if you pee in it?
no