And that’s not all. The survey — commissioned by the Water Quality & Health Council, a group of advisers to the chlorine industry trade association — found 40 percent of Americans readily admitted they’ve urinated in a pool as an adult. While it may seem obvious that this is not a good idea, Hlavsa explained the science of why it’s not: Urine reacts with chlorine, reducing the amount of chlorine available to kill germs. That bodily fluid, along with dirt and sweat, mixed with chlorine creates chemicals called chloramines, which causes red and itchy eyes.