From Longman Dictionary of Contemporary Englishnot hold waternot hold waterUNTRUEif an excuse, a statement etc does not hold water, it does not seem to be true or reasonable → hold
Examples from the Corpus
not hold water• His account of events simply doesn't hold water.• It may seem logical, but his argument doesn't hold water.• But there are times when this theory just does not hold water.• This argument just does not hold water. 