Dexter drinks a large quantity of water every day. And has regularly been doing so for years. It has been a running joke in my family that every time we know our son is coming to visit, either my wife or I will fill hurriedly the dogs’ water. From a 2016 blog post on petmd.com, the expert, a veterinarian from New York, used a phrase seemed to capture Dexter’s natural tendency to drink a lot of water, “(t)hese tend to be large-breed, playful dogs that like to amuse themselves by drinking water” (emphasis is mine). Which seems in character for Dexter. Mind you he is over ten years of age, and very fit, getting two walks a day and eating good-quality dog food for the last ten years.
While any unusual change in a dog’s water consumption may indicate certain health conditions, and can be diagnosed by your local veterinarian, some animals like some people just have a well-regulated system through adequate water intake. One site also has you consider that your current health, where you live (climate and at altitude), and your diet (excess sugar or spicy food) can necessitate additional water intake. Caffeinated beverages also can cause water loss through urination, as these are a diuretic. For good health, health advocates, and the Federal CDC (Center for Disease Control) recommend a half-gallon daily water consumption, which is equal to eight 8-ounce glasses.
It's a Dog's Life 