No, you and several others here are missing the point. They're not cheering him drinking water, they're cheering him giving the finger to the FAKE MEDIA. Same as with his lies. They don't care about whether what he says is true or not, they care that he's sicking it to the elites. To the LAMESTREAM media.
See, he's one of them. In fact, he's just like them. He sneers at the experts, at the coastal elites, at the pinheads in academia, etc. Just like they do. It just feels so good to have a president who feels victimized just like we do. So cheering comes naturally.
Viewed in the context of a cohort who believe politicians don't care about them, who thinks whites as a class are discriminated against more than blacks and who see themselves losing the culture wars, it's no wonder they cheer an act that is seen as a great big FU in front of the whole world.