IMHO, the teacher has a lot of explaining to do. I wouldn't want a child in his/her classroom if the teacher was aware of the li'l darlin's sharing drinks.
Back when I was in school you weren’t allowed to have a beverage in class. If you were thirsty you asked to go to the drinking fountain, and if you were lucky the teacher said yes. What the hell has happened in America that people can’t go anywhere without a damn water bottle.
To whom? The union will back her up even if she was the source of the booze. Nothing will happen.
When I went to school, no “refreshments” of any kind were allowed in the classrooms. If you were thirsty, you could get a drink at the water fountain between classes. Seems like this rule was not outrageously cruel at the time.