I have one of these dog waterers so that I don’t have to constantly refill her water bowl.  However, the dog is a little afraid of it.  She’ll take a few sips and then move back, eyeing it warily for a moment.  Then she’ll go back for a few more sips.  She’s afraid of the “burble” noise it makes when the air bubbles move to the top of the bottle.

Interestingly enough, my mother’s dog has the same problem, although her cat seems to enjoy making it burble.