Hi
Have you ever heard of an un-return valve? Someone asked me about one the other day and I have no clue what they are talking about.

It sounds like they may have been talking about a check valve, which allows water supply to flow in one direction but not the other. I've never heard it called an "un-return valve" but that is basically what it does. There is also a foot valve used to keep water from draining out of a well pipe when the pump isn't running. Those are my best two guesses.

Good luck!