Also make sure the water bottle has the ball on the end that's very easy to get water from. If you can tap it gently and the ball moves and you get water on your finger that is a good bottle. If it is springe loaded, and you have to push the ball harder to get water out then that water bottle is not good. To hard for gliders to get water out of them.
I think the idea that "our2girlz" has is a pretty good idea too.