The chlorine level isn't the issue - it's the urea reacting to the chlorine. There was even some neat research a few years back to figure out how much came fro

The chlorine level isn't the issue - it's the urea reacting to the chlorine. There was even some neat research a few years back to figure out how much came from urea from pee, vs. from other bodily secretions: https://www.npr.org/sections/health-shots/2017/03/01/517785902/just-how-much-pee-is-in-that-pool https://www.npr.org/sections/health-shots/2017/03/01/5177859... . > The scientists calculated that one 220,000-gallon, commercial-size swimming pool contained almost 20 gallons of urine After reading that NPR article, I can suggest another possible alternative; the pools might drain and refill their pools more often, rather than top-off when it gets low. Dry hair might not be that good of an indicator? I mean, I see people doing breast stroke with their head completely out of the water.