Green’s Dictionary of Slang

water wagon n.

1. a fig. state of sobriety.

1878–9		Garcia Tough Trip Through Paradise (1977) 65: Beaver Tom had forsworn his old love, whiskey, and was going to ride on the water wagon for the remainder of his life.
1899–1900		C.L. Cullen Tales of the Ex-Tanks 71: I’ve been riding the ice wagon for four months to a day. I have been up the pole for one hundred and twenty and odd days.
[1903		Nebraska State Jrnl (Lincoln, NE) 14 June 9/5: This palace [i.e. a bar] [...] where he always slides off the acqua vehicle] .
[1905		F. Hutchison Philosophy of Johnny the Gent 12: [I]i’s me on the sprinklin’ cart fer a while].
1905		F. Hutchison Philosophy of Johnny the Gent 16: Well, I’ve finally got it [i.e. alcohol] beat, old boy, an I’m the water wagon kid fer awhile, anyhow.
1908		N.-Y. American 30 Apr. in Fleming Unforgettable Season (1981) 57: McGraw made some slurring remark about McGann being an ice wagon.
1909		R. Cullum Sheriff of Dyke Hole 411: Guess you’ll ride the water-wagon fer six months — which ain’t wi’out ad-vantage to your stummick. Not a drop of liquor, mister, fer six month.
1915		Van Loan ‘Sporting Doctor’ in Taking the Count 41: Wasn’t Noah shut up in the water wagon [...] and wasn’t one of his sons a drinking man.
1920		N.Y. Tribune 8 Jan. 16/4: The Water Wagon [i.e. Prohibition], operated by your Uncle Samuel, will be quite a different cart this season. It takes an expert to fall off now.
1971		R O’Connor Irish 33: Many tend to ride the water wagon for long periods, with a rather sanctimonious, purse-mouthed air about them, and then fall off with a mighty splash.
2021		T. Swerdlow Straight Dope [ebook] — Don’t get me wrong, I’m glad you found your way to the wagon.

2. attrib. use of sense 1.

1910		Sporting Times 8 Jan. 2/5: The water waggon resolution week after New Year’s Day.
1910		Bulletin (Sydney) 13 Oct. 19/3: Invercargill (M.L.) – the town so frequently mentioned by Archdeacon Boyce and other water-waggon jehus.
1925		O.O. McIntyre New York Day by Day 25 Sept. [synd. col.] A young buck who won $1,000 on a year’s water wagon wager.
1932		J. Dixon Free To Love 33: You haven’t asked me about that water wagon proposition you wished on me, Kit.

In derivatives

water-waggoner (n.)

a temperance campaigner.

1912

Truth (Wellington) 22 June 1/2: The announcement of the water-waggoners that it is their intention to sacrifice national questions to their miserable fad and to vote for the boodle candidates.

In phrases

climb the water wagon (v.)

to adopt sobriety.

1905

‘Hugh McHugh’ You Can Search Me 19: He pulled a few snake tricks down there and in five minutes he had all the members of the Highball Association climbing the water wagon.

on the water wagon (also on the water cart, ...tank)

in a state of sobriety.

1896		Regiment 22 Aug. 311: [cartoon caption] [of a teetotaller] Sure he’s fallen out, sorr, an’ th’ ambulance is full, so he’s ridin’ asthride the water kyart’.
1909		H. Green Mr. Jackson 72: ‘And now, have a drink.’ ‘Nope, I’m on the water wagon.’.
1912		T.A. Dorgan Silk Hat Harry’s Divorce Suit 5 Jan. [synd. cartoon strip] I thought that you were on the water wagon.
1917		Western Times 10 Aug. 2/4: Alberta ‘On the Water Wagon’. It is now about a year since the Act came into operation in Alberta.
1919		Taunton Courier 19 Nov. 1/6: If you think we are going to allow any crank of a Yank to put us on the water tank, Mr Pussyfoot, miaow-wow!
1927		W. Edge Main Stem 125: Sometimes I gits on the water wagon an’ holes on tight.
1937		J.T. Farrell ‘A Sunday in April’ in Fellow Countrymen (1937) 429: I’m damn glad that I went on the water-wagon.
1939		Mencken letter 11 Jan. in Bode New Mencken Letters (1977) 437: Red Lewis [...] told me he was on the water-wagon.
		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 12 Oct. 10/6: Believe it or not — ‘Fat’ Campbell is on the water-wagon.
1941		Northern Miner (Charters Towers, Qld) 3 Feb. 4/3: I’m hanged if I know what young ladies like Flossie would do if we were all on the ‘water wagon’.
1944		Western Dly Press 11 Aug. 2/2: A London magistrate advised him ‘to go on the water wagon’.
1961		R.S. Close With Hooves of Brass 100: Now he was on the ‘water-wagon’ [...] his big eyes begging forgiveness of everybody.