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Thread: bathroom supply leak

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  1. #1

    Default bathroom supply leak

    I just installed new 1/2" nipples in the supply lines for a bathroom sink, along with new stop vales on each nipple. Now I have 2 leaks:

    One where one of the nipples connects to the elbow joint inside the wall (In this case, the connection between the nipple and the joint is right at the surface of the dry wall). The 2nd is on the other nipple, where it connects to the stop valve. I wrapped each connection with what I'd call 1 1/2 rotations of teflon tape.

    How tight should I have tighten each connection? Today I further tightened each hoping it would fix the leaks. No luck. Any suggestions? Could I have used too little tape? For the nipple/elbow leak, I suspected it could be the old pipe in the wall. But the nipple/stop valve leak is puzzling because it's a new nipple and new valve.

    I'd be grateful for any suggestions.

  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    The tape should be fine, but many folks on here will recommend that you use tape AND a light brush of pipe joint compound.

    Are we talking about a brass nipple, in a cast fitting in the wall, and a chrome plated brass valve? Then each fitting should be as tight as possible by hand, then 1 to 3 turnns by wrench. You have to "feel" it to some extent, but it needs to be quite snug.

  3. #3
    Senior Robin Hood Guy Ian Gills's Avatar
    Join Date
    Jul 2007


    If you mess the teflon up, it will leak. You need to get it nice and smooth. Redo the Teflon carefully, use pipe dope on top of that and try again. Be gentle when you first start screwing on to the tape. Try not to damage it. You want to minimze the threads cutting it.

  4. #4


    Thanks for the replies.

    Jimbo: You're correct about the materials except for the nipple: it's galvanized steel.

    I've never used pipe joint compound/dope... I'll go buy some. It just brushes on?

    Does it matter if the stop valves are pointing up? If so, how do I orchestrate it so that at their tightest point, they're still facing up?

  5. #5


    I have struggled with leaky threads on a lot of occasions. I have found that after a certain point, tightening it further is just going to make matters worse.

    I have found that when tying into old, dope can make the difference. I prefer to use the compound that is compatible with ABS and PVC, but that's because I'm a handyman and deal with a lot of plumbing leaks in all sorts of materials.

    It just brushes on with the brush that's attached to the cap. It helps if you leave the very end of the thread clear to help line up the threads to avoid cross threading. The stuff is really thick and can get rather messy - have a damp rag to wipe off the excess. That said, don't be afraid to slop it on, it wipes clean easy enough.

  6. #6
    Master Plumber Redwood's Avatar
    Join Date
    Dec 2007


    Quote Originally Posted by findmatt77 View Post
    You're correct about the materials except for the nipple: it's galvanized steel.

    What do you have for pipes in the wall? Are they galvanized as well?

  7. #7


    DuWayne: Thanks for the info, I'll try reconnecting using more teflon tape. If that doesn't work, I'll add a little dope.

    You got it Redwood... 1948 duplex: galvanized steel in the walls.


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