When i was a student, i also felt that all those rules are nonsensical

until the day i'm involved in the education field, then i understand why such rules are needed

some students, i tell you, they can turn a simple act of drinking into a disaster (eg. drinking turned into arguments and fight, drinking until the entire class is spilled with water). That's why you can't have nice things due to some people abusing a simple privilege.

Also some students do not just bring water to class, some of them bring coffee/milo/juices to class, so there is a potential it will dirty and stain the floor. I have seen many times, the classroom is dirtied with those watery stain until the teacher got fed up and barred students from drinking in class.

surely there are some incidents many years ago that necessitate schools to discouraged students from drinking in the class