How To Fix the RV Plumbing Leak from Vinyl Tubing

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Every RV we’ve ever had has flexible vinyl tubing someplace in it’s plumbing system.  But when that tubing is connected with standard PEX fittings, it’s almost guaranteed to eventually leak. In this video, I take you through a way to fix it: properly, and with off-the-shelf parts.  Check it out and save yourself a headache or two!


I’ve never come across an RV that didn’t have at least a little bit of vinyl tubing somewhere in its plumbing system.  There are a number of good reasons why manufacturers use it.

  1. The vinyl tubing can safely handle tighter bends than PEX will, and there’s usually a place or two in each RV where that’s called for.
  2. PEX doesn’t like to move, so it’s not a great candidate when the plumbing has to move – like in a pull-out exterior sink, for example.
  3. Because it’s flexible, vinyl tubing doesn’t transfer vibrations like a rigid material would.  So it’s frequently used right where the water pump connects to the plumbing to keep the plumbing system from being super loud and rattle-y when the pump is on.


There may be more reasons, but those are the most common ones I see.  But when manufacturers try to use standard PEX fittings for those connections to vinyl tubing, they can – and usually eventually do – leak.  The fittings just aren’t made for the vinyl tubing.  They’re really close, but not quite.  Eventually, they’ll fail.

This is a very common problem.  And your first instinct – when it happens to you – will be to get a hose clamp around there and tighten the bejesus out of it until it stops dripping.  That’ll work for a while, but will eventually fail too, because it’s still not the right solution.

After a long time searching, I’ve finally found the right solution, and you can see it in action in this video. Here are the links I promised you.

The Flair-It fittings in the video can be found on Amazon, here: Amazon’s Flair-It Fittings
The best price I’ve found on the adapter kit is on RecPro, here: Flair-It Adapter Kit from RecPro

So Now What?

You might be tempted (as I know I was) to go on a fitting swap rampage and remove all your vinyl tubing/PEX fittings and upgrade them.  But I think it makes more sense to just order a selection of fittings and some adapters to keep in your RV toolkit.  Then, when they do start to leak, you’ve got the parts on-hand to fix them appropriately.  That’s going to be my plan.  Or mods… any time I mod something, I’ll replace the fittings where I can.

Thanks for watching, and I hope this helps you out of a drippy jam!

James is a former rocket scientist, a USA Cycling coach, and lifelong fitness buff. When he's not driving the RV, or modifying the RV (or - that one time - doing both at once), you can find him racing bicycles, or building furniture, or making music. In his spare time, he works for a large IT company.

    26 thoughts on “How To Fix the RV Plumbing Leak from Vinyl Tubing

    1. Richard Timm

      Are there any PEX/vinyl connections in an EKKO that you would recommend changing out proactively? Thefitrv is an amazing resource. Thanks.

      1. James - Post author

        I’ve thought about that, and I can’t think of any that I would replace before they fail.
        I haven’t done any more in our own rig except the ones you saw, and the ones on our shower pre-heat setup (which were my test cases).

    2. Graham Smith

      I’m stretching my memory a bit but I seem to recall someone saying you could slip a little piece of heat shrink tubing on the fitting barb so that the flex tubing would fit tighter. But, with this shaky a memory, I cannot vouch for this as a solution.

      1. James - Post author

        Seems along the same lines as the Flair-It adapter.
        But Flair-it has probably tested their solution. You’d be a sample of one if you tried the heat shrink tubing.
        Still… it might work.

    3. Claude Cartee

      Thanks for another educational video. I understand your explanation of the differences and advantages of PEX vs. vinyl tubing. But what I don’t understand is why not just go with one type of tubing?

      If vinyl is more flexible, then why don’t RV manufacturers (and folks doing upgrades), just do everything with vinyl?

      And two more questions, how did you diagnose the leak? Was there a puddle of water? Or was the water pump running continuously?

      And I think I know answer to last question… RV plumbing systems need to be rated for how many PSI? 40? 45?

      1. James - Post author

        There are probably a lot of reasons why they do it that way.
        I’ll guess one is cost, and another is probably assembly time.
        PEX is pretty burst-resistant (if it freezes, it’s usually the fittings that fail).
        Besides… then there would be even more of a problem. The fittings work fine on PEX. It’s using the fittings on vinyl where they have problems.

    4. Koert DuBois

      Thanks for the clear explanation!

      Some of the long flexible vinyl lines in our 2021 Winnebago View have permanent fittings attached. They are about 8′ long but are in the same product family as the flexible lines used to attach the toilet plumbing.

      1. James - Post author

        Sounds weird. Like a super long toilet water supply hose?
        I haven’t come across that yet.
        If it were me, I might almost deliberately replace those with regular vinyl hose just so I knew what I was working with.

    5. Austin

      Nice solution but may be difficult to implement in areas with limited access. I found that re-crimping with Pex clamps on the tubing area that was already compressed seems to work, and I don’t think you are able apply the same amount of pressure with a screw hose clamp. The frustrating issue, as you mention, is that every unit appears to have this vinyl tubing mixed with standard Pex fittings, which is not supported by the respective part manufactures and will leak. This is part of why the RV industry has such a bad reputation. They know that every unit that ships will leak but continue to use improper materials.

      1. James - Post author

        Well, *any* plumbing solution is difficult to implement where access is limited.
        My PEX clamp buster, as an example, seems to take lots of room and swearing to operate!

        (Agree with you on the “why do they keep doing it this way?” sentiment.)

    6. Brian Nystrom

      James, I’m curious if you tried lubing the screw collar with silicone grease (or something similar) when working with the 3/4″ Vinyl tubing? That might make the process easier.

      1. James - Post author

        I didn’t.
        The tubing under the sink was a “thin” 3/4″, so I was able to get the collar on.
        The tubing I purchased at the home center was a “very fat” 3/4″ – and there was no hope there.

    7. Michael Yates

      James, you were literary a week late. I removed my toilet from my Winnebago ERA and replaced it with a Trelino dry toilet. The fitting for the old toilet was the 5/8″ hose and a hose clamp and a Pex end plug would not seal. After two trips to the hardware store I finally realized the fitting was a native Pex fitting and the fix was much easier. I already have some of the Flair it fittings in my kit, now I will happily add the extra ones you found that will fit the 5/8″ hose. Thanks and next time can you please put the video out before I have to struggle?

      1. James - Post author

        Sorry I didn’t get this out in time.
        You may want to hurry and order the adapter kit from RecPro – they’ll probably be sold out if this video goes viral.

    8. Ray Taylor

      Just discovered this problem in my newly acquired Leisure rig. Your solution works for flex to compression water line but I have flex to a T connection with 2 PEX connections. Used hose clamps that seemed to work for now but is there a solution for a flex to Pex union as I have several?

      1. James - Post author

        If you check the Amazon page I linked in the article, there are all different kinds of connections. I’m sure you can find something that will meet your needs.
        There’s a Tee – you could leave two of the connections as normal (use the white nuts, don’t add the rubber insert, and they work fine for PEX). Then use a rubber insert and the larger black nut on the leg that goes to the flex tubing. Should work just fine. Check out the link and I’m sure you’ll find what you need.

    9. Grant Hoover

      Months ago, Rigor RV Repair posted this issue on his YouTube channel. As mentioned, these incorrect clamps would not be allowed in housing building code. But I guess it’s okay for a $200,000 motorhome? Rigor stated that Winnebago was a prime violator. I hope Winnebago receives more intense push-back so they will correct it.

        1. Anthony Hassard

          I can’t thank you enough for this. Incredibly helpful!

          Do they sell that flexible hose insert and nut on Amazon? For some reason I couldn’t find it.

          Thank you again.

        2. James - Post author

          I couldn’t find them on Amazon, sadly.
          I debated buying a bunch of them and selling them in 10-packs myself on Amazon, but then I found the ones form RecPro.

      1. Claude Cartee

        Thanks for jogging my memory. I had remembered seeing the RigorRV video and now with James’ explanation, I am able to close the loop and better my understanding. I didn’t quite get it with the RigorRV video.

        Maybe James can use his pull with Winnebago to get them to do the right thing and stop connecting PEX/vinyl with improper connectors?


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