If my son drinks pool water, is this going to make him sick?

Depends on content: It is understood that kids often swallow pool water when swimming, on purpose or not. The standard pool with proper maintance should have enough chlorine in the water to supress common bacteria. However, agents like giardia are commonly found in wading pools and passes diarrhea.Cryptosporidia, another diarrhea producing agent closed a local water park last week.

Not generally: Pool water itself is not dangerous. However, its always possible that the water is contaminated, especially with human contaminants such as bacteria and human excretions. Having said that, millions of kids drink pool water every day without problems. Try to get your kids not to drink it, but if it happens, no need to freak out.