As much as it wants, dogs typically handle their own water consumption quite well. You should always provide water, if the dog drinks it all, provide more. On that note, I want to put this warning out as I am not a veterinarian. It is possible to die from "water poisoning," This occurs when all of the salts are flushed from the body and the individual cells are unable to stop water from entering them causing them to lyse (burst). This creates an anemic condition which could put the dog in shock. Like I said, dogs are extremely adept at maintaining their water intake so you shouldn't have to attempt to regulate it.