Dogs should have fresh water at all times, but it varies greatly on how much they need to drink. Some dogs get nearly all their water needs from their food, while other dogs that eat kibble will drink more plain water. Other things that factor in are how hot it is, how much exercise the dog gets, and even how dry the air is. Dogs lose moisture when they breathe, and the drier the air the more moisture they would lose. However, this isn't as complicated as it sounds, if your dog is healthy and you present him with fresh water, he will drink the amount he needs. If you water tastes bad, as has too much chlorine, filter systems, and even refrigerating it overnight will help it loose the chlorine taste, but most dogs aren't that fussy, and will gladly drink muddy water. Don't force water on your dog, if anything you will teach him water is bad. Remember the old saying, "You can lead a dog to water, but you can't make him drink." What I'm trying to say, is don't worry about it.
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