I would never bathe a child, I wipe them up with their own wipes even if it empties the box, call the parent right away and tell them they must pick up the child immediately. That is unsanitary for you and the other children when it's that bad.
Don't you have a rule in your contract? Mine states 30 days accident free AT DAYCARE before they can go without any covering, diapers or pullups. I'm not cleaning up messes like that on a regular basis.
As far as I'm concerned they are trained when they know they have to go to the potty and tell you or run there themselves. When they are placed on the potty and pee they are PRACTICING, but they are NOT TRAINED.