Both of the previous are great ideas. Also consider, if it is an older valve, that the main does not close completely, for a variety of possible reasons. We see that alot in older homes. You can confi ... read more
ConsultĀ a professional.
Whether it's 12" or 12' off the ground there are too many safety and code issues for the average homeowner to tackle. Better to do it right than to regret it later.