will not wash

will not wash

Will not be accepted or believed as true. That kind of excuse may have worked in high school, but it will not wash with me. The deadline for the paper is tomorrow, no extensions. He may be able to skirt the issue in some regions, but that approach won't wash in these parts—these people want straight answers.
See also: not, wash, will
Farlex Dictionary of Idioms.

won't wash

Will not stand up to examination, is unconvincing, will not work, as in That excuse about your sick aunt just won't wash. This expression originally alluded to a fabric that would not stand up to washing but by the late 1800s was used figuratively for other kinds of failure.
See also: wash
The American Heritage® Dictionary of Idioms by Christine Ammer.

something won't wash

If an explanation or idea won't wash, it will not be believed or accepted. Mr Aitken might try some such explanation if and when he returns. It won't wash. It won't wash to claim that what we eat is purely a matter of personal responsibility.
See also: something, wash
Collins COBUILD Idioms Dictionary, 3rd ed.

won't wash

will not be believed or accepted. informal
1998 New Scientist In the end, however, this argument won't wash.
See also: wash
Farlex Partner Idioms Dictionary

something won’t/doesn’t ˈwash (with somebody)

used to say that somebody’s explanation, excuse, etc. is not valid or that you/somebody else will not accept it: That excuse simply won’t wash with me.
See also: something, wash
Farlex Partner Idioms Dictionary
See also:
  • not for a second
  • not for a minute
  • not for a moment
  • aint
  • ain't
  • not for a instant
  • not for a/one minute/moment/second/instant
  • not by any means
  • by no means
  • hope not