on the wagon

Meanings

1. Abstaining from drinking any alcoholic drink, usually in the sense of having given it up (as opposed to never having partaken); teetotal.
2. Maintaining a program of self-improvement or abstinence from some other undesirable habit.
3. Used other than figuratively or idiomatically: see on, the, wagon.

Etymology

Originally on the water wagon or on the water cart, referring to carts used to hose down dusty roads: see the 1901 quotation below. The suggestion is that a person who is “on the wagon” is drinking water rather than alcoholic beverages. The term may have been used by the early 20th-century temperance movement in the United States; for instance, William Hamilton Anderson (1874 – c. 1959), the superintendent of the New York Anti-Saloon League, is said to have made the following remark about Prohibition: “Be a good sport about it. No more falling off the water wagon. Uncle Sam will help you keep your pledge.”