I have a link under the bathroom sink that I'm having a hard time figuring out. The link is a pretty steady drip when the faucets are running. The leak originates behind the nut that screws onto the coupling from the pipe coming out of the wall. From the p trap a pvc pipe slides into a larger metal pipe that comes out of the wall. When I removed the metal nut I discovered that there was no washer, so I put in a plastic washer and it still leaked. I then put in a rubber washer and it also leaked. Kind of at my wits end. Seems like the washer should fix the problem. I checked and the pvc pipe is not cracked. Any ideas? Thanks in advance.

Not all plastic washers are the same. Your washer should have a slight V shape to it so it gets squeezed between the PVC and the metall pipe. From what you have said that drip should have beeen there since the last time someone worked on that drain.

Are you sure that the leak is occurring at the compression nut of the adapter and not the threads where the adapter screws on to the galvanized pipe. If in doubt, remove adapter, coat threads with thread joint compound and reinstall.

I think this a good idea but that would mean the washer also leaked for the water to reach the threads but try it.

I'm absolutely sure the leak is coming from the nut and not the pipe. Any other ideas? I spoke with my local hardware store guy and he too is perplexed.:confused:

Do not take plumbing problems to ALL hardware store employees. Try what Harold suggested, it may fix the leak no mater which problem started it. This is only a drain so if you must, dry it well, coat it with Plumber Goop and allow to dry. Not what I would do if you were paying me but I'm not there and this does no harm.

I'm not sure I was clear. The leak is occurring at the compression nut... that is occurring before it reaches the threads of the adapter. Not sure why the washer isn't woking. Are you suggesting I apply the plumbing goop around the nut where the leak is occurring? Is it easy to get the hardened goop off if I need to remove the nut at some point?

Well, why not just replace the adapter?

Because the leak is ocurring before it gets to that point. Or do you mean the compression nut?

The compression nut, the nylon seal and the adapter are basically one unit. Cost is only a couple dollars. Something is not working properly so why not unscrew the adapter and replace it. That is assuming you have a threaded male or female PVC adapter and not just a compression nut on threaded piece of pipe.

What I have is the pipe that comes out of the wall. Then there is a piece attached to it that the pvc slides into and the compression nut screws on to. Hope that makes sense. So you are suggesting that I just get a new compression nut and see if replacing it fixes the problem? Something else you should know is that the pvc pipe has some give, meaning I can slide it a bit back and forth into the pipe even with the compression nut screwed on tight. Should it be able to do that?

You may have the wrong washer if the nut is tight and you can still slide the PVC.

I'm back to replace the adapter. When the compression nut is tightened hand tight you should not be able to move the trap arm. Again only a couple a dollars and an quick and easy task.

What size is the trap and arm, 1 1/4" or 1/12"?

Is the adapter metal or PVC?

I'm guessing the trap arm is 1 1/4" just because the compression nut is... seems to be a hair less in diameter though, because I'm able to slide it back and forth. The compression nut is metal not pvc.

What type of washer did you try, a clear beveled nylon or a flat black or gray rubber.

Tried both... neither stopped the leak.

The pipe coming out of the wall, is it a straight pipe with no threads or ring/rib or does it have a lip on the end pointing out from the wall?

The pipe that comes out of the wall is straight with threads. Comes out of the wall maybe four or five inches. There is another piece screwed on to the end of it. This piece is a short piece that looks to be copper. It also has threading at the end where the pvc pipe slides into to and that is where the compression nut attaches and is the source of the leak. I'm not a plumber (obviously :)) so I hope I'm explaining this well.

OK so the pipe from the wall has threads, the very next piece should slide inside the wall pipe and that next piece has a beveled washer and then a compression nut, right? That compression must have abeveled washer. Is this the point of the leak?

Again the pipe that comes out of the wall then has another piece (copper) screwed on to it... the pvc slides into it. The compression nut screws onto the copper piece. The nut is the point of the leak.