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webby7's avatar
webby7
Explorer II
Jun 17, 2025

Question re Water Pipes in Vintage 5th Wheel

Greetings, we own a 1996 5th wheel, permanently parked in a seasonal RV park. I've been doing a lot of remodeling and upgrades to it. I'm plan to replace both the bathroom vanity faucet and the kitchen faucet.

My question has to do with the water pipes in this rig.  By appearance & diameter, they would appear to be similar to Pex. I don't know for sure that they are original pipes, but I believe they probably are. I have attached a couple of pics of the under sink pipes. I measured them using my digital caliper, and they are 0.63". Half inch Pex at Home Depot measures at 0.625", so diameter is almost identical to modern Pex.

I was hoping to use Sharkbite shut offs to connect to my new faucet fixtures, and I bought the compression couplers at the following link, thinking they may work to transition from the grey pipes in this rig, to Pex pipe and then to 1/2",Sharkbite angle stops.  Anyone have experience with these grey pipes in vintage RV's?  Or have a better suggested method to attach new faucets to these existing pipes?  Thanks in  advance for any input!

7 Replies

  • StirCrazy's avatar
    StirCrazy
    Moderator
    Jun 27, 2025

    I feel like I have seen this before.  Don't use shark bite in any application that is subject to movement.  they are ok but I wouldn't use them anywhere you can't inspect them easy.  

    the best thing to do is get a 1/2" pex crimper some line and the fittings and actually replace as much as you can with pex.  also you can not use the pex fittings on Polly.  it will work for a while then start leaking as it is to soft and deforms.

    I have to redo my whole water system in my camper one of these years, what I did for now is got new rubber seals for all the fittings so it is tight.  that won't work for you unless you can find a threaded adapter from the PB fitting to the size you need for the faucets which is probably the best way to do it if you don't want to start replacing a bunch of line. 

  • joebedford's avatar
    joebedford
    Nomad II
    Jun 17, 2025

    Yeah, I forgot you're dealing with grey pipe. I don't have experience with those. Sharkbite on PEX and copper, I've used with great success. 

    • webby7's avatar
      webby7
      Explorer II
      Jun 17, 2025

      That was my original plan, but an RV guy on a different forum said that he used Sharkbite once on these older grey pipes and had leaks, so he went to compressed couplers, similar I believe, to those in my link above.  So I did buy a pair of those, just in case.  I think I'll probably try the Sharkbite fittings, and if there's any issue with them, I have a Sharkbite Removal tool, so I could take them back off and use the compressed couplers to transition from the grey pipe to 1/2" Pex, then to Sharkbite.

      I've used Sharkbite fittings over the years on plumbing repairs on RV's we've owned, and also have used them on plumbing at our site-built home.  I've never had any issue with Sharkbite fittings to date.

  • Grit_dog's avatar
    Grit_dog
    Navigator II
    Jun 17, 2025

    Don’t use Shark bites. 
    signed,  my buddy the plumber. 

  • opnspaces's avatar
    opnspaces
    Navigator III
    Jun 17, 2025

    I got this from a search of the archives. Here's a link to the related post. But I pulled the relative part out and pasted it below as well. 

    Link

    Old-Biscuit

    Polybutylene (PB) pipe is the gray tubing that was made between the late 70’s and mid 90’s.
    The 'Quest' fittings are no longer made or available

    PB pipe outside diameter is same as PEX so push on PEX fittings/valves can be used.
    Sharkbite (Home Depot) Gatorbites (Lowes), Flair-It and SeeTech/Watts will all work

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