from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Abstaining from drinking any alcoholic drink, usually in the sense of having given it up (as opposed to never having partaken).
- adj. By extension, maintaining a program of self-improvement or abstinence from some other undesirable habit.
Early 20th century American temperance movement. Originally “on the water wagon” or “on the water cart”, referring to carts used to hose down dusty roads. (Wiktionary)