on the wagon, to be

be on the wagon

To maintain one's sobriety; to abstain from alcohol. Jim's on the wagon again, so he doesn't want to go to the bar with us tonight.
See also: on, wagon

on the wagon, to be

To refrain from drinking alcoholic beverages. This term began life as being on the water wagon, referring to the horse-drawn water cart used to spray dirt roads in order to keep down the dust. The metaphor for abstaining from liquor originated about the turn of the century. It was given a definition (“To be on the water wagon, to abstain from hard drinks”) in Dialect Notes of 1904. B. J. Taylor used it in Extra Dry (1906): “It is better to have been on and off the Wagon than never to have been on at all.” To resume drinking is also put as to fall off the wagon.
See also: on