seltzer

noun

1. (sometimes initial capital letter) a naturally effervescent mineral water containing common salt and small quantities of sodium, calcium, and magnesium carbonates.
2. tap water that has been commercially filtered, carbonated, and bottled with no addition of minerals or mineral salts.

noun

1. a natural effervescent water with a high content of minerals
2. a similar synthetic water, used as a beverage

1741, from German Selterser (Wasser), a kind of mineral water, literally “of Selters,” village near Weisbaden in Hesse-Nassau, where the mineral water is found.