Have you tried switching his water bowl to stainless steel? Just an option in case its the bowl that is the problem. You can also try a water bottle feeder and just for info, dogs water needs are
approx one ounce water per pound of body weight per day. This varies of course depending on season/exercise/temps... If he is getting moist food, you can look on the label for what the moisture content is in the food and calculate how much he is getting through his food
