My kids are getting over this now, they caught from another child and I was talking to my friend and she said her dog caught it too!! Crazy!! I didn't know they can catch it from humans.
the dog "catching it" was purely a cooincidence. They cannot catch it from us.
In regards to the tap water, you are fine. I do believe the story about well water, however. It's not treated. Our tap water is treated with low levels of chlorine (bleach!)