Boys middle school water cooler

All the schools I've been in have water coolers instead of fountains, yet few students have cups or water bottles of their own. The boys middle school has anywhere between 1 and 5 cups set out at any given time. 
The very public nature of the cups makes me think the boys must get sick often, but maybe that's my American paranoia. 
I do find it interesting that few of them have their own water bottles. 
And for all the running around that they do, I don't see much of any water drinking happening.