Wiktionary
leak-proof
a. (alternative spelling of leakproof English)
Usage examples of "leak-proof".
They fixed up a huge bladder so that it was leak-proof, and put it to their mouths, and took turns breathing the same air over and over again, to see what would happen.
And another thing—you said it would take four months to make your ship leak-proof and you only had seven days.
They may possibly make your proposed procedures more leak-proof against the ingenious machinations of the Big Uglies.