pour/throw cold water on
US /pɔr/θroʊ koʊld ˈwɔtər ɑn/
UK /pɔr/θroʊ koʊld ˈwɔtər ɑn/
1.
to say or do something that discourages someone or makes them feel less enthusiastic about something
:
•
She was excited about her new business idea, but her parents poured cold water on it.
•
Don't throw cold water on his plans; he's really trying hard.