My hound Layla drinks a lot of water too. We call it tanking up. She has done this since we adopted her. I think it might be because she may have been deprived of water when we was with her old owners. However it might be a good idea to have a general check with the vet's office just in case there is something else going on. (Especially if this is a new development). Also with Layla, it appears that she's drinking alot but when she moves her head from the bowl, I swear half of what she's drank runs back out onto the floor. We keep her water bucket on a boot tray with a towel and a rug underneath it to catch the run off.