If you’ve ever wondered why people are asked to shower before swimming, there are millions of reasons: microorganisms in the pool water that most people would rather not have there. Everyone has bacteria on their skin, and even though most of it is harmless, there are reasons to limit the quantity that gets into swimming pools. We also have bacteria in our digestive systems, most of which is useful to us, helping digest food. In fact, science has determined that the number of bacteria in the gut is greater than the number of cells that comprise the human body. A study of hygiene determined that for every 14 or 15 people who don’t shower properly with soap or shampoo, and rinse well, one gram of bacteria-laden feces is contributed to the pool water.

We all know that public swimming pools have filters, and chemicals, typically chlorine, to get rid of harmful germs. Some people may assume this cancels the need to shower before entering the pool. Our germs will soon be killed by chlorine, right? Well, that’s true, and many pools now have ultraviolet filters which also destroy germs. In these filters, water is pumped through a cylinder where bright ultraviolet light kills microorganisms. Ultraviolet filters are particularly important for getting rid of cryptosporidium, a parasite that causes diarrhea and is somewhat resistant to chlorine.

The problem with assuming chlorine will take care of bacteria is that when chlorine kills harmless bacteria, free available chlorine (FAC) is used up. The dead bacteria remain in the water, and the chlorine forms chloramines, which are the cause of swimming pool odor, and do not kill germs. More chlorine must be added to kill any harmful organisms still in the water. Besides bacteria, cosmetics, perspiration and urine combine with chlorine to form chloramines. The chloramines cause irritation to eyes and skin. If you can detect a “chlorine” smell, the concentration of chloramines is too high and there is not enough free available chlorine. Just shower well, and help keep the pool safe.