Maybe he's wolfing it down too fast. But if I were you, I would call your Vet and ask him/her if there is a problem. Call your Vet to be safe!
I would say take your dog to the Vets. There is bad doggie flu going around in dogs but your dog might have just have drank too much water. If your dog's got an infection it will throw up water clear like liquid. Cause my dog had endometriosis and she did the same thing.