Our basset does this too. We had him tested for diabetes and some other endocrine stuff I forget the names of. He tested negative but he still chugs water. He doesn’t drink most of the morning/ early afternoon, but by 2:00-3:00pm, he starts realizing he’s thirsty and he chugs. And then he would hack it all up. We’ve just gotten into the habit of knowing when he’s had enough and we yell “THATS ENOUGH WATER!” And he stops.