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

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
References in periodicals archive ?
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.
And, of course, that logic won't hold water anywhere but in the minds of the council and its cohorts.
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.
Get a size that's a little too large for the trunk so it won't hold water against the wood.
With solid advice from experts in the field, The Architect's Guide to Preventing Water Infiltration shows how innovations in today's construction techniques simply won't hold water if they don't follow the fundamental ground rules necessary to keep water out.