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Sep 9 2017

RV Plumbing: How to Fix Water Supply Lines – RV Life #fix #it #plumbing


RV Plumbing: How to Fix Water Supply Lines

When something goes wrong with plumbing in your house, the fixer can be at your door within a couple of hours. But when you discover a leak in your plumbing, it`s that not simple. Not too many plumbers make RV house calls. Whether you`re on the road as a snowbird or find a problem while prepping your RV for Spring. getting a repair done at an service facility could mean days, even weeks, just waiting for an appointment. That s an untenable situation, especially for snowbirds.

In many cases a break or leak in an RV water supply line is often a literal snap to repair. That s because the water lines in most RVs are plastic PEX pipe. They are not buried inside walls and are usually accessible for easy repair. PEX stands for cross-linked polyethylene. Typically, this pipe is connected using a special tool and metal fittings that can complicate the fixing procedure for RVers. The good news is you can skip the special tool altogether. Instead, use a variety of different plastic fittings, some of which snap the stuff together, making repairs quick, easy, and relatively inexpensive.

What is PEX Tubing for the Plumbing in my RV?

PEX tubing in homes is color-coded for hot and cold. In RVs, manufacturers typically use translucent non-colored PEX for all plumbing runs. Further, two sizes are used, 3/8-inch and ½-inch. These are the standard size because the outside diameter of the tubing is about 1/8-inch greater than the called-for size. Also, PEX is inexpensive. At one hardware store bulk 3/8-inch may set you back 50 cents/foot.

Additionally, PEX is ideal for both cold and hot water (some up to 200 degrees) plumbing. Typically, the rating is on the tubing itself. Chlorinated water is not an issue in terms of tubing or health safety.

What Tools Do I Need?

While working on water lines. you just require a tool to cut the PEX tubing itself. You can use a utility knife, but a tubing cutter designed for PEX ensures a clean, even edge. This is also a requirement for a leak-proof connection. These cutters are less than $10. I usually go with a PVC pipe cutter, which makes a clean edge and can be used on PVC pipe as well.

Fittings that are Required

When you need to change out your water lines. there are a variety of different fittings available. They range from simple couplers that allow you to fix a break to tees that are for jobs when adding a new run. Others include adapters that allow you to shift from one size of tubing to another. Want to add a shut-off valve to turn the water off to your toilet (or whatever) without shutting down the whole RV supply? There are fittings for that, too. Here are a couple of styles particularly useful to RVers when it comes to plumbing:

  • Plastic compression fittings: A brand found in many hardware stores is Flair-It. These are relatively inexpensive. We bought a 3/8-inch tee fitting in a small-town hardware store for $3.99. Simply, cut the tubing squarely and ensure there aren t any burrs on the tube. Unscrew the nut from the fitting, and slide it back over the tubing. Now, push the tubing over the fitting flare, rocking it back and forth until it comes to a full stop against the fitting. Then, tighten the nut by hand until secure. Need to take it apart? Just reverse the order of assembly instructions.

The assembled tubing inserted into the fitting. (*Note: The tube stiffener not visible as it s inside the fitting)

So, what are advantages of this? They are less expensive than quick-connect fittings. However, the disadvantages are when you are working in a cramped area. It can be a bit difficult to maneuver your hands in place to shove the tubing onto the fitting and to tighten the nut.

  • Quick-Connect fittings: Made by Watts, these are a little more costly. A 3/8-inch coupler for joining two pieces of tubing is around $4.00. Using these fittings in a cramped area is much easier. Again, cut the tubing square and check for burrs. Slide the included tube stiffener into the end of the tubing until there`s resistance. Now, keep pushing until the tubing comes to a complete stop. Finish the job by inserting the included collet clip on the joint.

To take this connector apart, remove the collet clip. Then, push the collet firmly against the tubing face and pull the tubing out of the fitting.

Aside from an easier fix in a cramped space, there`s less water flow impediment in this design, as opposed to the plastic compression style. Both insert material into the flow, but the tube stiffener appears to block less water flow. Additionally, the Watts fittings allow you to attach to a host of other plumbing materials, including copper and CPVC. What`s more is the quick-connect fittings and the plastic compression fittings will connect directly to polybutylene tubing.

You may find other brands of quick-connect fittings to meet your needs as well. Some of the larger stores sell other brands of fittings, and of course, price comparing is the order of the day.


this article would only be informative to the most mechanically ignorant, which most rvers who are do it yourselfers are NOT (only do it youselfers would even glance at a subject such as this). Plus it is gravely inaccurate by claiming that plumbing is easily accessible in RVs. In my motor coach and I believe the majority of rvs the exact opposite is true and this fact is of concern to RV owners as their vehicles age and the possibility of plumbing problems (leaks) looms on the horizon.
Please vet your articles carefully. Misleading novice owners is a disservice which I am sure is the opposite of what you want to be.

I won t be so harsh as len, as I thought this was an informative article, however, I agree, from my experience traveling around the country in RVs, that the plumbing can often be pretty difficult to get to .

Blazing A Trail says

I do not consider myself mechanically ignorant , however I was not born with the knowledge of RV maintenance or repair and did not absorb it through osmosis. Although it seems that some readers may have those talents. The rest of us poor ignorant fools appreciate back to basic type articles like these so that we can make sure we are headed in the correct direction or learn the basics.

Thank you for not assuming we are all know-it-alls and that we DIYers learn as we go. DIY is the only option for many of us, due to pure necessity. I take great pride in tackling mechanical issues that many women I know would not attempt. It amazes me what we can do when we have to and these type articles are instrumental in helping.

BD Williams says

At what point did RV manufacturers start using pex? I am in a 2002 and still have pretty drastic water pressure limits that I would like to get away from. even if the piping is pex won t I still be limited on water pressure due to the cheap plastic water pressure valves on the toilet and other places? I already had two of these Dometic 385314349 Water Valve Assembly pieces fail due to plastic cost cutting assembly that I first thought was from water pressure.

Randy Jackola says

My bigger issue in my 1996 discovery with gray pipe is how to install new pex with virtually no access to shower and bath runs. Most piping must have been installed early during body construction. I realize that my motorhome is old but is still nice inside and out. I have been searching in vain for info on easy or tricks-of-trade articles. I would like to trade up, but mine is still virtually new and we love the quiet ride of the d.p.

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