I needed to replace an old toilet valve. It was connected to a 1/2" nipple coming out of the floor. The nipple came off as I unscrewed the valve. So I put a new valve at one end of the nipple, then screwed the nipple (with the valve attached) into the female threaded connection in the floor.
I can't see the connection I made in the floor, it is about 2" below the subfloor. I have connected pipe before, and I have no reason to believe it is leaking, but I can't see it to be sure, so it's bothering me. I gave it 4-5 wraps of monster teflon tape (the blue stuff) and tightened it pretty well, the same as I normally do. Any good way to find out, aside from a water spot in the (brand new) bathroom below?
A water spot is certainly a dead give away, but one way to check is look at the water meter with everything turned off. There is a little red dial in the face that shows small amounts of flow, if that is dead still, chances are good no leak. Check it for movement over say, 1-2 hours.