At my school we (very luckily) have a rule that students can only drink water in the classroom during the day. They can have milk or a juice with breakfast/lunch. I am very strict about having only water in class, and I make sure I set a good example by only drinking water in class in front of them as well. This has never really been a problem except for one student. Her parents (this is an elementary class so kids can’t really buy things themselves) fill her water bottle with SODA all the time before school. I’ve politely written home about, mentioning that it’s a school rule that kids can not have soda at all. Yesterday I (privately) called her out on it again and she cried about it saying she “just can’t drink water unless it’s flavored or soda or juice”. I can’t imagine a parent ruining their child’s health like that. My town has amazingly clean water you can drink of the tap for free. We have many water fountains with cold water all over the school.