I am extending an existing 1" PVC water line from my well to a yard hydrant. I am using PEX-B pipe and brass fittings. One end will be connecting to an existing 1" PVC pipe using a Threaded Male PVC to Threaded Female Brass fitting. What should I use on the threads? At Hydrant it will be brass to brass, what should I use on the threads?

  • Answers go down there, Jim.
    – isherwood
    Jul 14, 2021 at 14:58

1 Answer 1


I would use pipe joint compound labeled for general use, including PVC. Really Teflon tape would do pretty well since this is outside where a slight seep (not as much as a drip) at first would be OK. Sometimes with pipe joint compound a slight seep will seal itself over a few days.

Either pipe dope or Teflon tape, and sometimes both, on the brass to brass. I had to use both to get some brass to brass and brass to copper joints outside to seal. I even had to put pipe dope on the female threads. This was outside above ground and when I finally gave up it was still seeping. A week later it was dry.

Are brass to brass threaded connections allowed in contact with soil? Is this connection in soil contact or will it be in a box? I didn't think PEX-B connections could be in contact with soil.

  • Would I put the compound on first or the Teflon tape if I use both?
    – Dean
    Jul 22, 2021 at 17:05
  • My inclination would be to put on a light coating of pipe joint paste onto the male threads and then put the tape over that, but I have seen recommendations to do it the other way. Personally, I would first try the pipe joint paste alone, without the Teflon tape. Have you looked at the use of plumber's hemp fibre along with joint paste? On YouTube search for videos on plumber's hemp for sealing pipe joints. I wonder if coarse button sewing thread would work? AFIK you always use pipe dope with fibre, i.e., don't combine Teflon tape and any fibre. Jul 22, 2021 at 18:56
  • AFIK you always use only pipe dope with fibre, i.e., don't combine Teflon tape and any fibre. Since this is outside (for garden irrigation?) it is OK to put pipe dope on the female threads too. Flush the joint at full flow before connecting to any device that could be plugged with mobilized pipe dope. Jul 22, 2021 at 19:07
  • This is for well water line. I am using black poly pipe (160psi), poly pipe fitting and brass fitting. Poly pipe fitting is connecting to PVC on one end and Brass on the other at yard hydrant. So, sound like you are saying to use the thread sealant on all and if leaking, then use Teflon tape and thread sealant. I planned to just put thread sealant on the male fittings.
    – Dean
    Jul 23, 2021 at 0:42

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