How much do dogs drink usually?

I have two- a 35kg (about 77lbs) lab and a new rescue dog Collie/Doberman of 25kg (about 55lbs) and I have been noticing how much more my smaller dog drinks than the big one. They are both an ideal weight for their build and eat the same food - raw fed. Before I had my collie I used to refill the 2 litre water bowl every morning and it was always half full. Now they are getting through two bowls a day and I have been keeping an eye on them and realised my collie will drink half a bowl of water at a time and more than twice what my lab drinks. He actually gets less exercise than the lab as he is too nervous/aggressive to be let off the lead. Is this anything to be concerned about? My lab is very healthy and my Collie has some skin problems due to obsessive licking and biting at himself and terrible bad breath due to poor diet before we had him. They are both about 2. It is unlikely to be psychological for my Collie because although he was badly abused by his previous owners he was overfed and rather fat when he got taken in. I suppose that does not mean he had adequate water tho?

Whenever a dog suddenly starts drinking excessive amounts of water you should always take it along to the vet as it could be an indication of a serious problem. Kidney disease in dogs causes both bad breath and strong thirst and you need to get this ruled out.

Your Collie X should drink somewhere around 1 ounce per pound of weight, so, about 55 ounces, or 7 to 8 eight ounce cups per day. This is not a hard and fast rule, but when trying to diagnose a previous dog's over-drinking, I had to keep track of how much he drank. Vet told me a 32 pound dog should be drinking about 4 -eight ounce cups/day, not more than 5. So there is some leeway. Yours are finishing 4 liters per day between two dogs, and your Lab drinks about 1 liter/day, leaving 3 liters for the Collie. That's alot. In ounces, I believe there's approx. 34 ounces to a liter X3= 102 ounces??? So, if my math is correct (!), she's drinking enough for a dog twice her size,more or less, or 12-13 eight ounce cups per day. That's close to what my Saint Bernard drinks, and he's alot bigger than her. Different people/vets etc may give somewhat higher figures, but this is in the ball park. And it's not as if they are on a salty food, either.I would not allow my dogs to drink half a bowl of water at a time; you put in 2 liters, so, she is drinking an entire liter in one shot. If that's true, she is drinking about 4 eight ounce cups at once. Drinking so much at once can help lead to bloat. When was the last time she saw a vet? With skin issues, dental disease and over-drinking of water, you should get her in to the vet. They should do bloodwork on her which can help to diagnose a problem, if there is one. You absolutely need to do a urinalysis on her...that will be very telling, as well. With those two tests, if there is a disease causing this, and there are a few that cause polydipsia/polyuria (excessive water drinking/excessive urination), you will be in a good place to get an answer.Are you aware of the color of her urine? Does she pee excessively? Does her urine look almost clear and not yellow? Does she have accidents in the house or is she primarily an outdoor dog? At the vet, they will also test to see if she is concentrating her urine, which will also give clues regarding a potential health issue.Some dogs are just big drinkers and do not have a medical issue. But it seems to me that she is drinking an awful lot...enough to get it checked, as soon as you can.