The eternal lie of the pools that turn blue if you pee in them

Mel Magazine:

If you pee in the pool, it’ll go blue! There’s a special dye in there, designed to detect urine, and it’ll billow around you in a big, embarrassing, pissy cloud, and everyone will know you’ve done it, and you’ll be hounded out of town as a known pool-piddler.

Everybody knows that, right?

Except it isn’t true. It doesn’t even stand up to any scrutiny as an idea — what chemical specifically detects wee-wee?

How many of us were told this as kids? How many of us believed it?