1
general::
Phrase(s): pour cold water on something
1. Lit. to douse something with cold water. • Pour cold water on the vegetables to freshen them. • I poured cold water on my head to cool myself off. 2. and dash cold water on something; throw cold water on something Fig. to discourage doing something; to reduce enthusiasm for something. (Alludes to cooling passion with cold water.) • When my father said I couldn’t have the car, he poured cold water on my plans. • John threw cold water on the whole project by refusing to participate.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, throw cold water on. Discourage or deter, as in Cutting my year-end bonus poured cold water on my loyalty to the company, or Hearing about the outbreak of cholera threw cold water on our plans to visit Bolivia. This term, with its image of putting out a fire with water, at one time meant "defame" or "slander"; the modern meaning dates from about 1800.
American Heritage Idioms