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NanciL's avatar
NanciL
Explorer II
Jun 16, 2015

Question for you plumbers

I am installing a water filter on the incoming cold water supply to our washing machine.
The connection on the filter is plastic threaded female and I will be using a male threaded plastic (PVC) on PVC piping.

I have always been told that you don't use Teflon tape when you are going plastic threads to plastic threads.

Is that correct ? Or should I use it ?

The instructions with the filter say "never use pipe sealant or pipe dope"

just looking for the above question answered not suggestions on using PEX, etc

Jack L

16 Replies

  • I hate thread to thread plastic, it always leaks usless tape or pipe sealer is used. Either one works.
    But I glue plastic whenever possible.
  • Another vote for the tape. No reason not to and it will keep the threads from galling.
  • I am a plumber. Use Teflon tape for plastic to plastic threaded connections. Do not use any type of compound.

    Bruce
  • You are absolutely correct! NEVER use Teflon tape on plastic/nylon NPT fittings. The tape will cause the fittings to distort when screwed together. I know there are those using Teflon tape where they shouldn't with success but that don't make it right. Even the RV manufactures use Teflon tape on pipe threads but it's not good practice. If you poll the plastic/nylon pipe manufactures, they'll support my comments.

    Richard
  • Well I was going to say use PEX it easier but to answer your questions.

    I always use teflon tape. It seems when I haven't in the past the connection would leak or eventually leak.

    The instructions caution against a sealant or putty because these are petroleum based and may eat through or damage the PVC.

    So feel free to use teflon tape.

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