it does no hold water

Not hold water / it does no hold water: diz-se de algo que pode se provar ser falso, uma afirmação que parece não ser correta, que não tem consistência

A:“I believe that dinosaurs were on the earth 6000 years ago.
B: “That theory doesn’t hold water. The earth isn’t that young!”

“When she told me that she thought the sun revolved around the earth, I told her that it doesn’t hold water. The earth moves around the sun! “http://www.idiomeanings.com