Pool season has arrived. Suspicion will soon mount about that child who managed to swim for four hours straight. When grandpa jumps in the pool straight after his five hour drive to see you with no bathroom break in between, eyeballs will roll. Questions will arise about that barbecue guest who consumed a six pack and floated in an inner tube for the rest of the day. There will be queries. There will be polite declinations to that offer to swim. "You put a lot of chlorine in your pool, right?" a friend might ask before dipping her toe in the shallow end.
Is it, or isn't it, OK to pee in the pool? That depends on your definition of "OK". Here is what experts have to say about urine in chlorinated swimming pools:
The CDC says: "Irritants in the air at swimming pools are usually the combined chlorine by-products of disinfection. These by-products are the result of chlorine binding with sweat, urine, and other waste from swimmers. As the concentration of by-products in the water increases, they move into the surrounding air as well." So more pee in the pool = more chlorine by-products in the air around indoor pools.
The Water Quality and Health Council says: "...if chlorine is combining chemically with contaminants like urine, then it is not available to destroy germs in the pool that can make swimmers sick with diarrhea, swimmer’s ear and various skin infections." In other words, since chlorine gets used up combining with urine and other organic compounds, it isn't there to kill off the bigger, badder germs in the pool.
But then, a biochemist piped up on Sense About Science: On Ryan Lochte's famous Jimmy Kimmel Show interview (the one where he admitted to peeing in the pool), a biochemist named Stuart Jones said, "An Olympic size pool contains over 2 million litres of water and a single urination is somewhere in the region of 0.2 litres. To have any significant effect on the overall composition of pool water you'd need a serious amount of peeing."
What can we draw from this meager assortment of research? We can conclude that it is still gross and bad to pee in the pool, and you shouldn't do it. Peeing in the pool produces chlorine by-products that can irritate eyes and the respiratory system. However, the amount of pee that it takes for any noticeable effect is up for debate. It depends on the size of the pool, as well as how diligently the pool's chemical balance is maintained. Pooping in the pool will make people more sick than peeing will, but nevertheless the CDC still advises all swimmers to shower with soap and to refrain from urinating in pools to limit the amount of organic compounds that they add to the magic soup that is swimming pool water.