Since we joined the town pool this year, I've been doing some research on how to keep my kids safe in the water. To say I've been enlightened is an understatement. For one thing, I never really understood why they have you shower before you enter a pool. I figured, why bother? you are going to get wet anyway! But, if everyone practiced this simple procedure–and better yet, washed their bums with soap AND water, then the chances of illness from pool water would be greatly decreased.
There is a special term–Recreational Water Illnesses for the kinds of infections you can get from swimming in public areas. Recently, a friend told me about how her daughter was hospitalized after visiting a water park due to an infection. So far, my kids have been lucky enough not to get sick, but it's only the beginning of the season!
The CDC has a great site that gives tips on how to avoid these illnesses. (Link here) You can even order free test strips to test your town pool water. Don't just trust that your public pool is safely chlorinating the water–there are key questions (on this site) that you can ask them to make sure.
Also, keep your kids out of the water if they have open sores (i.e., scraped knee) or diarrhea. The latter can contaminate the water with a certain bacteria called cryptosporidium that will not be killed by chlorine and can last for 7 days in pool water. And, emphatically tell your kids NOT TO DRINK THE WATER! My son was driving me crazy at Sesame Place because he kept sticking his hands in his mouth while in the water.
For moms, make sure you wash your hands thoroughly after using the bathroom. Fecal matter has ecoli that can cause problems if ingested. So, be sure to clean bottoms thoroughly. Bring some antibacterial gel to make sure you get everything off your hands before jumping in the water. Also, don't change diapers next to the pool (you could contaminate benches). Check diapers often and/or ask your kid if they have to use the bathroom regularly.
If we all practice these simple procedures we can keep nasty bacteria infections away. Another helpful article: Medicinenet.