Water only. My school has a water-only policy, so they can't take juice or other drinks (but we don't give them those anyway at home). I'm buying them all RTIC cups today, actually, so that they can have ice-water all day at school.
in the cafeteria they can buy milk (2%, skim, and skim chocolate), lactose-free milk, and soy milk.
Before someone asks, this is a public school in a very low-income area (more than 51% of the students get free/reduced price lunch).
ETA Sorry - I didn't read your entire question. My kids will be going into grades 2, 4, and 5.