Green’s Dictionary of Slang

1. voluntarily refraining from alcohol.

1889		United Service I 155: ‘No, thanks,’ was the reply ; ‘I’m on the water-wagon.’ ‘Oh, I know that; but I mean as medicine’.
1896		H. Blossom Checkers 167: Arthur took early occasion to state that he was ‘on the water-wagon.’.
1901		Hegan Mrs. Wiggs 123: I wanted to git him some whisky, but he shuck his head. ‘I’m on the water-cart,’ sez he [DA].
1902		Boston Globe Sun. Mag. 21 Dec. 7–8: If a student has ‘hit the benzine can’ too hard on the night before he is apt to be anxious to get ‘on to the water wagon’.
1910		Wodehouse Gentleman of Leisure Ch. v: ‘Talking, however,’ said Jimmy, ‘is dry work. Are you by any chance on the wagon?’.
1912		Van Loan ‘Sweeney to Sanguinetti to Schultz’ in Ten-Thousand-Dollar Arm 59: We’ve reformed [...] It’ll be five weeks to-morrow since we got on the cart.
1914		T.A. Dorgan Indoor Sports 22 Jan. [synd. cartoon] ’Member the time Mansfield was on the cart and we caught him dipping his bread in the brew.
1919		F. Hurst ‘A Petal on the Current’ in Humoresque 105: I’m on the water-wagon.
1920		Ade Hand-made Fables 12: They had been on the Cart for two full days.
1922		M.E. Smith Adventures of a Boomer Op. 52: As Mr. Phillips says, I am O.W.W. (On The Water Wagon).
1924		P. Marks Plastic Age 273: He did his drinking elsewhere, confiding to his cronies that Carver was on the wagon.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 301: Water Cart (or Wagon), On The: A Teetotaller.
1936		D. Stivens Tramp and Other Stories 49: Bloody poor way of spendin’ the afternoon . . . keepin’ on the water-waggon . . . she’ll have to make up for mucking my afternoon.
1938		F. Durbridge Send for Paul Temple (1992) 223: What the devil’s the matter with you, Horace? Are you on the wagon?
1940		N. Mitford Pigeon Pie 243: He was now on the water-waggon.
1946		D. Stivens Courtship of Uncle Henry 168: Metho Bill, the town’s fulltime drunk, swore off the drink and went on the waggon to make sure he would be sober for the match.
1951		Cusack & James Come in Spinner (1960) 310: Tea it had to be since he had decided to go on the water-wagon.
1953		J. Thompson Alcoholics (1993) 67: I’ll be about ready to go on the wagon.
1968		J. Alard He who Shoots Last 93: You should go on the wagon yourself.
1971		Wodehouse Much Obliged, Jeeves 27: Ginger’s practically on the waggon, so there were no cocktails before lunch.
1971		R.D. Pharr S.R.O. (1998) 122: ‘You can’t even remember I’ve been on the wagon for five months’.
1979		B. Gutcheon New Girls (1982) 9: He [...] announced he was on the water wagon.
1981		J. Ellroy Brown’s Requiem 43: You got that look, nervous like, of a juicehead on the wagon.
1990		R. Malan My Traitor’s Heart (1991) 286: He was technically on the wagon but [...] a drink or two on a special occasion wouldn’t really hurt.
1991		R.G. Barrett Between the Devlin 21: ‘What I should do is go on the wagon for a month’.
2006		D. Mitchell Black Swan Green 314: So how long [...] we staying on the wagon this time, then, Frank Moran?
2010		L. Redhead Thrill City [ebook] I guess if you’re going to fall off the wagon then the conclusion of a police pursuit was the time to do it.
2011		Sun. Times 6 Feb. 23/3: In 2000 she went on the wagon.
2012		T. Robinson ‘So Long, Johnnie Scumbag’ in Dirty Words [ebook] ‘I thought you were gonna say you were on the wagon’.
2015		L. McInerney Glorious Heresies 201: Tony had taken care with his disguise since his tumble from the wagon; today he was clean-shaven, fragrant and ironed.

2. in ext. use of sense 1, adopting any form of self-denial, e.g. celibate, abandoning one’s use of drugs.

1959		P. Roth Goodbye Columbus 65: [in context of excessive consumption of fruit] [I] would have to spend the following night, sadly, on the wagon.
1976		H. Selby Jr Demon (1979) 19: His love life [...] was extremely active. When he first started working [...] he went on the wagon, so to speak.
1997		N. Barlay Curvy Lovebox 33: You want some fuckin’ gear or you wanna go on the fuckin’ wagon the rest of your days.