Swallowing a little pool water is almost inevitable. Your stomach acid is insanely strong, so a tiny bit of chlorine is no big deal. It’s like a drop of lemon juice in a volcano.
But if you gulp down a lot, your gut might rebel with nausea or an upset stomach. Chlorine isn’t designed for your digestive system—it’s designed to nuke germs in the water.
The cool science bit? Chlorine reacts with organic stuff (like, well, us) to keep water disinfected. It’s a chemical sacrifice for our safety. Pretty awesome, if you think about it.