I found this in a CNN article when looking up impetigo to see what it was..
Mom worry: Could my child get impetigo from the swimming pool?
Facts: Not a concern. This bacterial skin infection, characterized by itchy blisters, scabs, or sores, is spread by direct contact with someone who's infected or from sharing contaminated towels or clothes -- not from water. "Kids get impetigo more often in the summer because they get cuts, scrapes, and bug bites then, which leave them particularly vulnerable to bacterial infections," says Robert Baltimore, M.D., a professor of pediatrics in the infectious diseases division at the Yale University Medical School.
Once your child is exposed to impetigo, it can take two to three days to develop symptoms. If it's limited to a small area, your doctor may suggest a topical over-the-counter antibiotic such as bacitracin or a prescription-strength antibiotic like Bactroban. Either of these may be enough to cure the infection and prevent it from spreading. Parenting.com: The savvy mom's guide to sun safety