To not drink water (or whatever else is needed to remain hydrated) because of some concern over going into the dugout, getting it from one team or the other, or whatever other reason is just plain stupid. Do we not understand how important it is to keep yourself hydrated, on and off the field? God knows I've learned the hard way.
I've dealt with a bout of kidney stones recently, the cause of which can partly be attributed to my not drinking enough fluids in general. I can assure you that I won't do that again. We are all supposed to drink our wieght in water in ounces every day, so if you're 225 lbs., you're supposed to consume 225 ozs. of water
pr day. Admittedly, I doubt many of us follow this guideline, but I'm sure trying to, that's for sure.
During summer ball I bring a cooler jug (usually a 1- or 2-gallon one) of cold water with me onto the field. I set it aside near the backstop's corner, usually out of sight or so. I make sure that I use it whenever I can, which is usually once every other inning at a minimum. If I run out, or when I do spring games, I have no problem whatsoever going to a duguout to grab a drink from either a cup or water bottle. In my D1 or other higher level games, as well as the nice schools in D2 and D3, liquids are provided. Some venues even have water fountains in the dugout. I never hesitate to use them.
My own health is far more important than some stupid feeling of pride, vanity, or anything else that some might otherwise be too worked up about.