Whenever I'm not racing, I'm volunteering. I'm usually the head of the "Transition Mafioso" (the mean gang that monitors the transition area) at the tris or dus, but I've been the water girl many times. You can't mess it up. Just have it out and they'll take it. If they lose 10 seconds on the day because they had to walk for a millisecond, then too bad. You're out there helping them stay hydrated and safe so they can just deal.
I love to volunteer and always get many thanks from the athletes when I do it. In return, I always thank every volunteer and police officer when I race. It takes so much to put on an event, as having run a couple- I know how hard it is to find volunteers. Do it- you'll have so much fun!!!!