Long ago, my husband wrote a long report about some people whose job it was to sew together the pages of books. He called them sewers, and it wasn't until the whole thing was typed up that he realised that he'd have to rewrite the whole thing and call them sewing machine operatives.
Sewers (that is, drains) are marvellous, wonderful things, and I'm sure we'd all be much less healthy and fragrant without them. The entrance to the one in our front drive even has a mysterious iron ladder going down inside it, and I've sometimes been tempted...
...but not that tempted!
Anyway, the word in itself is nasty. Sewer. It sounds like someone spitting out a toad they've found in the soup.
Word Not To Use Today: sewer. This word is from the Old French essever, to drain, and before that probably from the Latin words ex, out of, and aqua, water.