| There are medical conditions which can cause drinking large amounts of water (this is called "polydipsia", and it's a symptom of various conditions, most notably diabetes) - did you mention it to your vet the last time you were there? "Checking out great" doesn't mean that the vet was looking for anything specific, it means that he saw nothing obvious. It can also be an obsessive-compulsive thing. Or it could just be a habit he has. Or it could just be that he needs a lot of water. I'd definitely take him to the vet for this, specifically, and I would expect blood tests. Before you start trying to control the behaviour, I think it's important to rule out any possible medical causes for it. Good luck. |