pour cold water on sth

1. (lit.) staviti u vodu; potopiti vodom, zaliti, sipati  

“Pour cold water on the vegetables to freshen them.”  ” I poured cold water on my head to cool myself off.”

2. (kol.) obeshrabriti (nekog), pokvariti (plan i sl.)

“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.”