A childhood belief about swimming pools

my afterschool teacher(who held afterschool at her home) told all the kids that she put a chemical in the pool the reacts when you pee in the pool be forming a red trail behind you. i was always so scared to go swimming because i thought i might accidently leak urine into the pool. every 5 seconds i looked behind me and one time i was just seeing things but i thought i saw the red trail and started crying because i thought i peed in the pool and didnt know it