Minor etymological note: the word plumb describes something that's hanging vertically. It comes from the latin word plumbum (lead). When people wanted to make sure something was vertical, they'd hang a lead weight from a string, and align the string with whatever was supposed to be vertical. Even though we've moved on to different metals, we still call them plumb bobs, and we still say that a vertical part of a house…
I knew "plumbum" meant "lead", but I'd always assumed the etymology of "plumbing" was just that pipes were historically made of lead. thanks for posting!
I was plumbing a wall when I dropped my hammer and had to start all over.