I have a threaded joint to a shower valve that has a small leak. I used teflon tape, however the joint isn't fully sealed. Ive read on the proper technique and such so I'm not looking for how to do it better. Any suggestions/advice on the fix. Ide rather not remove the valve as its not the easiest to get to but I will if there are no suitable alternatives.


Shower valveShower valve joint


If you can cut out the copper elbow and fitting, on the next one you can try this method:

1) Use a small amount of pipe dope on the male threads prior to applying no less than 3 full wraps with Teflon tape.

2) For Teflon tape, they make some varieties that are 'extra thick', which help compress to fill the gaps.

3) Before assembly, another thin application of pipe dope (Rectorseal 5 or similar) on top of the Teflon can help seal up the threads of particularly pernicious leaks.

It may also be worth confirming that the taper of the threads on your valve and your fitting match.

If you cannot or do not wish to remove the fittings or valve, the scorched-earth approach is to use a two-part epoxy putty. Mix the stuff and apply it firmly around the entire threaded area and fitting. The fitting should be bone dry. For extra strength on 'field-expedient' fixes using 2-part epoxies, I've included a small strip of fiberglass tape to embed between two small layers of the putty. It's not necessary, but it might help enhance the strength/longevity of the repair.

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  • I assume the teflon tape is the longest lasting solution. I guess just looking at the life of the epoxy would give an indication on how long that would last? It is on the cold water input so it wont be facing any heat. – Owen Broady Jan 15 '18 at 22:19

Yes, you can redo the threaded connection and hope for the best, but it's best not to use them at all if possible.

Instead of using the threaded connection, often you can solder the 1/2" OD copper to the inside of the threaded connection on the valve. For example, this Delta rough-in valve allows the use of either 1/2" NPT threaded connections or soldered 1/2" OD copper on the same valve. I'm suggesting removing one or all of the threaded connections and just sweating the copper directly to the valve, thus eliminating the threads from ever leaking (since you're not using them.)

Delta rough-in valve

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  • 1
    Before you sweat 1/2" copper tubing directly into the valve body you must remove the cartridge and any plastic parts, right? – Jim Stewart Jan 16 '18 at 0:00

If you do not want to mess with soldering, you can purchase PEX fittings and use PEX.

Cut the copper pipe farther down and put a PEX adapter on it. Then run PEX to the valve. Jeffs solution is the more robust way though.

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