“Everyone does it.” “It’s all water, it all goes to the same place.” “Fish pee in the water all the time, why can’t I do it?”

Well, bad news, pool-peers: Your excuses are no longer valid.

According to an eye-opening video from the American Chemical Society, peeing in the pool may do more harm than you think — even if no one can prove you did it.

According to the video, while chlorine and other chemicals keep pool water clear (and not green, like the pools in Rio), the chemicals can react with dirt, sweat, urine and other chemicals on swimmer bodies to create harmful reactions — including red, stinging eyes and respiratory problems like asthma.

Oh, and that nostalgic chlorine smell at the pool? That’s caused by pee.

For more information, watch the video below.

Alex Hider is a writer for the E.W. Scripps National Desk. Follow him on Twitter @alexhider.