Coons can and DO have parasites that can make people very sick. They can kill dogs and cats. You were correct in washing their bowls. My daughter played in the dog water once when she was a toddler. We put a stop to that, but she got very sick and her pediatrician did some investigating and when he found out we had coons and outside dog water he was very concerned. She turned out to be okay, but we started dumping the water in the evening and refilling in the morning. Also, we kept her away from the water.