RV Plumbing Repair: PEX Tubing and Fittings

RV Plumbing Repair: PEX Tubing and Fittings

Last updated on April 20th, 2019 at 11:57 am

RV Plumbing Repair with PEX

Modern RVs, made in the last 10 to 15 years, are plumbed using PEX tubing, sometime called PEX pipe,  for the fresh water system. In fact, most new homes and commercial buildings use it too. It is so much cheaper than metal pipe and because it is flexible it is easier and less expensive to install as well. It also makes it easier to do your own RV plumbing repair.

There are many colors of PEX tubing but Red, for hot water and Blue for cold water are often used.

PEX Tubing Coils
PEX Tubing Coils

Frugal RV manufactures may use white or non-colored PEX tubing for both hot and cold lines.  The manufacturer of our RV made this choice.

Manufactures can choose plastic or metal fittings to join lengths of PEX and connect the PEX tubing to appliances and fixtures. Regardless of which kind of fittings used, the fittings are connected using a crimp ring that is set with a special crimping tool. These tools are priced starting around $50 and go up.

What crimping tool you need depends on the type/brand of crimp rings being used. After the ring is crimped, a gauge should be used if determine of the crimp is within specs.

Metal PEX Fitting and Crimp Rings
Metal PEX Fitting and Crimp Rings

Luckily, for the RVer who wants to do his own RV plumbing repair, it doesn’t have to be that complicated or expensive. There are two common fitting types that do not require expensive tools. While special tools for these fittings are available and can make the job easier they are not expensive. You may find you don’t even need them.

The only special tool that I have purchased is a PEX cutter for around $15. You can use a good sharp knife but the cutter makes it a whole lot easier to get a nice straight cut. Especially in tight spaces. The fact the cutter can also cut smaller sizes of PVC pipe and rubber hose makes it a worthwhile investment to my mind. My advice would be to spend enough to get a cutter made of metal.

PEX Cutter Tool
PEX Cutter Tool
PEX Cutter
PEX Cutter

I found my PEX cutter at Lowes but here is one that is similar at Amazon.com Eastman 95117 Pex And Plastic Pipe Cutter

Types and Brands of PEX Fittings

Flair-It Fittings

The first fitting system I’ll cover is likely the most common one you’ll find at RV parts stores. The fittings are made by a company called Flair-It.

Their advantage is a relative low price and ready availability.

Their biggest disadvantage is the need to push the end of the PEX tubing over a flair on  the fitting. It takes some strength and can be difficult to do in a tight space where you can’t get enough leverage. A wrench and a pair of slip-joint pliers are all you need to tighten the compression nuts. Flair-It makes a special wrench that may be needed in a tight space where pliers would be difficult to use. But, so far, I’ve not needed one. The wrench costs about $15.

Flair-It PEX Fitting
Flair-It PEX Fitting

Quick-Connect or Push-On Fittings

The second most common repair fitting is the quick-connect or push-on type. Common brand names are SharkBite and Sea Tech but there are others.

The big advantage is ease of use. You literally just push the ends of the PEX tube into the fitting with next-to-no pressure and you’re done! Honestly, I can hardly believe these fittings work. But they do.

The disadvantage is the higher cost of the fittings. But you may decide to the extra cost is worth the convenience. I think I have.

Quick Connect PEX Fitting
Quick Connect PEX Fitting.
The black insert is placed into the end of the PEX pipe to prevent deformation.
Quick Connect PEX Fitting
Quick Connect PEX FittingDepressing the tan plastic ring back against the fitting will release the PEX Tube.

You can buy a special tool called Removal Disconnect Tool for under $5 that makes it easier to depress the release ring. But with a little effort you can depress it with your fingers or pliers..

Disconnect Clip Tool
Removal Disconnect Tool

Apollo Lockfit Fittings

There is another style of quick connect fitting that is a hybrid of the two types above. The brand name is Apollo Lockfit. I discovered them when I bought a couple of them at Lowes when I wasn’t paying attention. They have the same easy insertion as the standard quick-connects but have a compression nut like the Flair-It fittings. But these compression nuts can be finger tightened. No wrench or pliers needed.

Apollo Lockfit PEX Fitting
Apollo Lockfit PEX Coupler Fitting
To use this type of fitting The PEX is inserted into the fitting, then the locking nut is turned to hide the blue band. You can see a proper connection on the left. The release ring cannot be depressed until the locking nut is loosened.

Plumbing Adaptors and Fittings of Interest to RVers

There are fittings and adaptors for every plumbing need. Below are just a few that you may want to have on hand.

PEX Plumbing Adaptors
PEX Plumbing Adaptors
Adaptors are needed to connect plumbing to appliances like water heaters and pumps and fixtures like faucets and toilets.
Above is an Apollo Lockfit male adaptor. Below is a Flair-It Female adaptor.
90 degree female adaptor is
This 90 degree female adaptor is commonly found in RVs and used to connect toilets and shower faucets among other things.
Flexible Supply Line
Flexible Supply Line
Used to connect a male adaptor to a toilet or faucet etc.
Can be useful if you are replacing a toilet with a different model/brand and the connection doesn’t line up with the pluming.
Male Plug
If you have an Atwood water heater you need a couple extra drain plugs. (See: RV Water Heater Drain Plug Failure)
The same plug may be used to plug a female adaptor allowing you to restore water to the RV while making a repair.

The fittings pictured above are only a sampling if the fittings you may want to have on hand. For example you may want to keep one or two 90 degree couplers and one or two ‘T” couplers. An inspection of your RV will give you a good idea of what spare fittings you may need to have.

Remember if you ever need to replace a section of PEX tubing you will need two couplers And don’t forget you’ll need a length of new tubing. I keep about 3 feet in my parts box.

I hope you have a better understanding of how PEX plumbing and fittings work and have enough confidence to do your own RV plumbing repair if necessary.

As always, if you have questions, suggestions or comments please use the comment box.


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62 Responses to "RV Plumbing Repair: PEX Tubing and Fittings"

  1. I have a question–recently purchased a 1994 Damon Intruder in excellent shape, how far back have they been manufacturing motorhomes with this type of “plumbing?”

  2. I don’t know when RV makers switched to PEX plumbing. It’s been at least 7 years because our 2007 fifth wheel has it. I suspect it depended on each manufacture as to when they switched to PEX.

    Our first fifth wheel, a 1989 model, used a gray tubing. It was similar in appearance and installation the plastic was not PEX and the fittings and crimps were different.

  3. Hello, Steven!
    I am updating all of the plumbing in a 79 nomad I am redoing and I have noticed that the previous plumbing includes both 3/4 and 1/2 inch sections of metal pipe. Is there some necessary reason for a diameter change (for water pressure or something)? I am going to replace all the metal with PEX and would prefer to just use one size for the entire project, if that is standard. Thanks!

  4. First, I’m not a pluming expert, just an RVer who likes to save money by doing my own repairs, so I am not speaking with authority here. I can see no reason for having the larger 3/4′ but the fact that your RV has it makes me wonder. You may want to consult an RV tech with the proper knowledge. That said, the two RV’s I’ve owned have been been only 1/2 tubing. The first was the gray plastic, our current 2007 uses PEX.

  5. Hello I am looking for some plastic elbow fittings connecting the shower faucet to the water supply (which is PEX with a metal fitting)in my RV Alfa fifth wheel. Everything I’ve been sold at Home Depot and Ace Hardware has not worked. I have pictures of the elbow. The problem is that the male opening that attaches to the PEX line has some beveling on it. I think it is a pressure fitting? Help!

  6. Got to an RV shop to get the fitting… it seems it may be an RV industry special item. An alternative is to cut the PEX below the fitting and replace it with a common one. I used flexible supply lines to connect the PEX to my faucet.

  7. Thank you for the excellent information! My RV has the metal crimp rings you show in the first picture. What is the best way to remove these from an existing pipe (without damage to the pipe), and what can I replace them with afterwards?

  8. Jan H.

    You should be able to cut the crimp part of the ring of with a good diagonal wire cutter. Or abut anything that will cut wire.

    It’s difficult for me to advise you about replacements. It’s likely you will need to replace the entire fitting since there is no wat to put another crimp ring on without a special tool. I like the quick connect fittings just because they are so easy to use. However I’m not sure how the would work is this case since the the PEX line will be deformed by the the crimp and that may affect the seal of the quick connect. A compression fitting would be the safest option.

    Ask an RV tech for his advice.

  9. Steven,

    Your article is great, very well written and very descriptive Thanks!

    Got a question though, We replaced the kitchen faucet and used regular cut off stops, All three are leaking, Do you think that maybe the use of teflon tape on the connections might be the problem?

  10. It would depend on what type of cut off/shut off valves you use I suppose. However most I have seen use compression to make the seal and teflon tape is not necessary. Maybe the valve itself is leaking?

  11. Thanks for your reply. It is a leak, but coming from the connection area. I think the tape may be the problem and will take it a part and redo it.

  12. I see you said that you use flexible lines to your faucets. I wish to do the same. What brand of connector did you use to go from the pex to the flex?

  13. Thank You Sir, for the very good information you have posted…I am replacing my toilet supply line…I can not find a flexible 1/2” water supply line,with plastic conectors,as you have pictured.I do have one with metal ends.will that work with out damaging my toilet threads?Do you remember where you got the one pictured?

  14. Thank you, Steven for your advice.I did get a Sharkbite male end for my pec tubing,then ran the new 1/2” water supply line with metal conectors to my new Thetford toilet….Guess what……No leaks under pressure…Thanks again for such a informative,and real world site……

  15. Thanks for the info. I just spent all day at the local big box stores trying to figure out how to find new Flair-It fittings. All along, I was thinking it was different than the white PEX and the SharkBite would not fit. So glad I found your post.

  16. Thanks for the very useful article! There were some other questions about the grey tubing used in earlier RV’s. I just did a repair on our 1991 Fleetwood Southwind which has this grey tubing, and after cutting off the leaking fitting (I could not remove the crimp ring, so I cut off the pipe) I was able to use a push-on fitting, just as described in this article. Works fine.

  17. Have a 92 Pace Arrow with the gray tubing and copper elbows. Will the Pex fittings go into the gray tubing? It is 1/2″. Need to replace a section, make a right angle and attach to kitchen faucet. Thanks for all your info. I do all work myself and have seen several issues here that I had already figured out.

  18. Yes they should work fine cliff. Rather than replacing the right angle, you may want to consider using a flexible supply line to connect the pipe to the faucet. The parts you’ll need are available at home improvement stores.

  19. Steven any idea where I can get that flexible supply line you show? The one on my water pump is leaking, but I can’t find another one like it. thanks! – Lisa

  20. The supply line pictured is meant to connect regular fittings to faucets, toilets etc. What was used to connect your water pump may be different – RV manufactures can be very creative. It could be be just a length of regular garden hose. Best advice is to remove it and take it with you to an RV store or home improvement store. Take a few photos if you cannot remove it.

    It may also be that the RV store may be able to offer an alternative connection system.

  21. Hi Steven, I need to install a shut-off valve to my water pump as I am hooked up to the city water. Can I use metal fitting with 1/2″ per line and pex crimping rings?

  22. got a 1998 golden falcon 35 foot . drained my tanks and saw water running down steel beam under slide out and a big bubble in insulation under front end of rv . cut a hole to drain the water but having hell of a time finding the leak spot without removing all the insulation. having hard time finding any specs on this rv too , any ideas ?

  23. I’m not sure you really want a shut-off valve, but rather a check valve. The water pump should have a check valve that prevents back flow. If you can reach the pump easily then it would be best to repair the check valve in the pump. On the other hand, in our previous RV the pump was really hard to reach so I did in fact add a check valve inline. The plumbing guy at the hardware store should be able fix you up with what you need. At least go and look for yourself and see what is available.

  24. You most likely will not find specifications for your RV even if they once existed. But, except for high-end motorhomes, RV owners manuals are usually a joke anyway. Sorry to say John, but you are going to have to do what it takes to fined and repair the leak. Once you remove the insulation to get a visual on the tank you should be able to determine where the leak is. If it is not obvious, the leak may be where the plumbing drains into the top of tank.

  25. Michael Mayville · Edit

    Hi Steve,
    I am removing a Thetford Recirc toilet to put in a Thetford Aqua V. I need to run a water line from the vanity to the new toilet. I own a 2004 Trailmanor and it is a tight fit in the bathroom. So I am guessing I need to remove the vanity to get to the plumbing under the washbowl. I am not too sure but I think it is using clear PEX under the sink. I do not see red and blue like I had in my 2005 Hi-Lo. What fittings do you recommend to T off the cold water side of the sink?


  26. You will likely need to add a T fitting on the cold water line before the line gets to the sink faucet. The type of T you will need depends on if you will be using PEX to reach the new toilet or a flexible supply line.

    Take a good photo or two of the plumbing under the sink and go to the hardware or plumbing supply store. A competent sales clerk should be able to put together the supplies you’ll need.

  27. Question.
    I have a 2013 kz rv with a suburban water heater.
    We broke the elbow adapter connecting the pic pinte to the hot water heater last night and need to replace. Can
    I use the one lowes sells? The blue hawk Pex elbow adapter? This one does not require cinch clamps. Do I need cinch clamps? Or can you recommend the part I need? I am new at this whole rv thing .

  28. In winterizing my RV today I find the cold water connection that goes into the hot water heater is broke off flush. The tank is metal, looks like alum. Am I safe to assume I can use an “Easy Out” to get the broken piece out of the tank. As I said it is broken off flush.

  29. Just purchased an 82 King’s Highway 32′ and have leaks coming into the carpet when we start the pump. We cannot find a schematic anywhere to even know where or how to start checking. Can anyone help? References to an RV plumber? Anything?

  30. I went to winterize my Montana fifth wheel turned valve on water pump and turned the valve on water heater only has one valve on water heater . antifreeze still goes into water heater with valve turned both direction. If valve is bad how can you remove compression hose from valve has the barb fitting

  31. Hi, thanks for all the great information! I have a 1991 36.5 Terry 5th wheel. My wife and I live in it full time at Dick’s RV Park in Great Falls, MT. The other day I noticed the hydrant that we use was leaking from underground. The weird thing is my water heater stopped working the same day. The weather out here already changed so it is very cold out and we have to have our rv hose heat wrapped. Well I had to remove our hose for the hydrant repair and with a slight movement it broke right off and began to spray a nice dose of water to compliment the 20 to 30 degree weather. The water here is loaded with plumbing killing chemicals.
    We are financially challenged so, I am forced to do all the repairs myself. So far I replaced the a/c motor, an a/c electrical board, the power inverter, toilet, kitchen sink and faucet, thermostat, door knobs and deadbolts, and water heater. I replaced the water heater last summer and we had very nice hot water for a while now. It was a plumbing nightmare to install. When I noticed we lost hot water I went out to inspect it. It was cold enough to where I couldn’t feel my fingers and while checking the wired connections broke one of the quick connect wires off. It got bellow 20 out last night and I hope the tank did not crack or explode. The main issue right now is getting the water back on. The park has already fixed the hydrant and now I have to get the hose back on without any leaks, hence my issue. I cant have any leaks at all or it will start a giant mound of ice. I get the hose connected and turn on the water. First a few drips, so shut it off and try again, boom water hose pops of and sprays water everywhere. Second attempt a Home Depot run (they are right around the corner from me) but when you actually get a person to help you, trying to explain my problem is a challenge and if you dare mention it is for an rv there heads start to spin. I have the grey pipe that you say is in yours. So I have it down to one grey pipe sticking out of the hook up compartment that I have to connect to the hose, through a pressure regulator. Today is probably the last day I have before we get hit with snow and near zero temps. Any tips or advice would be greatly appreciated.

  32. I have never experienced cold weather that severe so I cannot offer much help with your water hose problem. Maybe someone else reading this will be able to help. As a temporary solution, can you just fill your fresh water tank and use water from that until you can sort things out? Keep your water hose inside when not filling the water tank so it doesn’t freeze between fills.

  33. I just purchased an older model RV.. A1994 Coachman Leprechaun. It has just one water intake on it. I cannot get it to fill the tank. I have turned all the valves every way they can be turned if I swap sides on the water pump, it will fill, but will not pump to the outlets. If I swap them back, it will pump to the outlets, but will no fill tank. Any ideas?

  34. Mike, Your RV likely has a fresh water fill port somewhere. It could be on either side or the back of the RV. Use Google image search to find “rv fresh water fill” and view the images to give you an idea of what to look for on your RV.

  35. Thanks for your reply.. The tank has no fresh water fill.. We took the tank out of the vehicle and it just had three small lines. 1 was the drain and the other 2 were overfill tubes. Guess I’ll have to put a fresh water fill in it. Thanks again for your quick response..

  36. We have a leak in a fresh water line that runs from one side of the motorhome to the other. The leak, of course, appears to be in the middle of the motorhome and inaccessible as the line runs above the fresh water, grey and black tanks. There is access at each side so I’m thinking that I can fish a line through and then splice it at each end of the existing line. The existing line is braided flexible PVC, not PEX so the various 1/2″ PEX fittings you show in the article will not fit on the end of the PVC. I suppose I can just splice in a piece of PVC and use
    connectors and hose clamps. Any thoughts or suggestions? Thanks.

  37. I do not know the proper fittings and/or adaptors necessary for your repair but I have no doubt they exist. I recommend contacting the manufacturer’s customer support for specific advice when possible. If not a trusted RV repair shop would be next best. I wonder if, instead of splicing in a patch, you might not be better off replacing the whole length of the line if that is possible.

  38. I have a 2010 Itasca with a small water leak under kitchen sink. It looks like it is coming from the T that the ice maker line comes off of. Are those an easy fix?

  39. It should be an easy fix, but you didn’t give enough information (the type of plumbing and fittings used) to offer specific advice. If your RV uses PEX plumbing the easiest fix would be to use push-to-connect fittings.

  40. I installed a new outside water intake fitting and connected the old cold water line using a shark bite fitting.
    Problem it leaks.
    How to fix ????

  41. Replacing a Dometic toilet with a Thetford. my plumbing is polybutyl and i have to make a 90 degree turn to connect with toilet’s 1/2″ input fitting….. having trouble fining a fitting of that type

  42. I’ve seen some ‘creative’ ways RV manufacturers use to plumb toilets. When I have had to working these toilets what is worked for me is a flexible toilet connector. There is no need for special fittings or getting the length just right to make the connection.
    Just choose the proper length toilet connector and the right fitting for the supply line. A quick-connect fitting on the supply line makes to job simple. I have also put a shutoff valve on the supply line just in case something goes wrong with the toilet.

  43. I have a leak that seems to be located under the heater (not water heater). Water has come up under the vinyl on the floor in the kitchen and there seems to be a slight wavyness in the floor where the water is staining under the vinyl. I recently had the furnace repaired and the leak seems to have started after that. Is there any way to access the hoses that might lie under the furnace? I have a 1998 Jayco Eagle. If it is not that, how easy is it to replace all the hoses, especially around the fresh water tank (they are moldy and full of sand).

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