Definition of water wagon in US English:

water wagon

noun

  • 1A cart, usually a barrel or tank on wheels, carrying water; specifically one used to water the streets by sprinkling water from small holes as it goes along; = water cart. Chiefly US in later use.

  • 2Informal (originally US). In various expressions referring to abstinence from alcoholic drink, especially in "on the water wagon".

Origin

Mid 18th century; earliest use found in Daily Advertiser. From water + wagon.

Pronunciation

water wagon

/ˈwɔːtə ˌwaɡ(ə)n/