My kids middle school has restrictions on water bottles?

If the students come into cl with a water bottle that has already been open all the teacher has to do is open it up and smell it. They would be able to tell if it had alcohol in it. And it wouldn't take that much time. That is a stupid rule that makes no sense!!! In my opinion if a teen wants to drink they will find a sorts of ways to do it. So making that rule isn't going to stop them from doing it.