Used metaphorically 'drawing a lot of water' is not as Matt describes it. Literally, when we say that a big ship draws a lot of water, we mean that its keel is deep underwater. Metaphorically, if somebody draws a lot.of water this means they take up a lot of room, they are important. It is used to describe a politician's influence: Donald Trump draws a lot of water in Florida. Its use in this context seems inappropriate, as if the writer were as confused about using it as Matt is about reading it: all bets are off.

The reference is to "draw water", which is the collocation used for taking water from a well. It is suggesting that the politicians are able to take a lot of political power from its source, I think. It's not a metaphor that I've ever seen before. Some people would say that using fresh metaphors is good writing, although news sources usually prefer to recycle old ones.

(I'm a US native speaker). I haven't heard it before. I've heard the phrase "A is carrying water for B," meaning that A is an obedient servant of the policies of B. To me, the phrase "drawing water" refers to how far below the surface a large ship goes. "That ship can't get into this harbor because it draws too much water. Only vessels with a very shallow draught can enter this harbor."

I've never heard it before.. I would assume the writer is trying for Matt's meaning, but badly.