Not glass, of course-I was thinking more of an insulated canteen-something that would hold maybe a gallon of water & keep it reasonably cool for an hour or two. I imagine the wait at the water fountains will be pretty long. Something like this, if it's permitted, would reduce the number of visits required.
by the way, do you know how many water fountains there are on the site? I read that there will be 'some' but hopefully it will be in proportion to the crowd. (If you're expecting 3,000 people then I'd think you'd put in more than say, 3 water fountains. On the other hand, if you're only expecting 300 then 3 water fountains should be plenty.)