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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.

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 repairs, 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

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 under $10.

Flair-It PEX Fitting

Flair-It PEX Fitting

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

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.

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.
The same plug can 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 repairs if necessary.

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

7 Responses to “RV Plumbing Repair: PEX Tubing and Fittings”

  • Ad Addison:

    This a great piece of information Thanks..

  • Jack:

    Thanks Steven,
    I was wondering what they used.

  • David Robinson:

    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?”

  • 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.

  • Jess:

    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!

  • 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.

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