won't hold water

not hold water

To not be or not appear to be true, verifiable, or able to be supported by facts. The image is of a container with holes in it—a metaphor for a position or argument containing "holes" (errors or gaps in reasoning). I'm afraid that excuse just doesn't hold water with me—you still should have had plenty of time to complete the assignment and print it. That old claim has been debunked so many time that it just does not hold water any more.
See also: hold, not, water
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

won't hold water

to be inadequate, insubstantial, or ill-conceived. Sorry, your ideas won't hold water. Nice try, though. The prosecution's case wouldn't hold water, so the defendant was released.
See also: hold, water
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
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References in classic literature ?
That won't hold water; it doesn't commend itself to reason."
That would amount to sheer dereliction of duty to protect the Philippines' interests in this case, and the kind of suspicious dismissal of basic good sense that won't hold water with the public.
Another possibility is using slurry that contains bentonite, which is a clay, to seal ponds that won't hold water, including those on farms.
But he said: "That won't hold water for much longer because for the first time cyber crime, online crime, is about to get added to the crime figures - and I think that will show a very different picture from the one painted by the Tory government.
We need to remember that if there were cracks in that reasoning back then, it certainly won't hold water now.
What you're told won't hold water. Unfortunately, you'll still be left dealing with all your original suspicions.
A friend who is raising two young daughters in a Modern Orthodox community worries that the truthsabout marriage and familythat she grew up with won't hold water for her own kids.
The assumptions that they might have used to decide whether to form a captive in the past won't hold water today.
Malfunctioning pipes, drains, drippy faucets, and sinks that won't hold water are now your problem and your expense.
Of course, that won't hold water as an excuse when I'm being read the story about the outdoors writer breaking an outdoors law in the office of the big guy back at the paper.
But feigning sickness, claiming the goldfish has just died or you've suddenly developed a particularly bad case of dandruff, won't hold water anymore.
When a tub drain won't hold water or the finish looks bad, the usual fix is to replace it.
This explanation is very clever, but it won't hold water. We might pipe it onboard were the pedigree of the Sea Goat not so archaic.
Get a size that's a little too large for the trunk so it won't hold water against the wood.
Remember, this is a performance-based business; if you perform well, whatever they may feel won't hold water.
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