You guys say he is waterproof, which would be fine with me if it weren’t for the fact that we see water pouring out of him. You could say his internals are waterproof, but when we get glimpses of them there are exposed servos and circuits. It’s okay, ESB is still my favorite movie, but this In my mind is a flaw.
Some electronics actually do spit out water to get liquids out of components like speakers.
Related question, are Star Wars droids slaves?
Yes, effectively.