What Size Water Lines [Including Pex Pipes] Are Used In RVs?

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  • Post last modified:January 5, 2022

PEX piping and tubing are popular amongst the RV community. However, how big is the water line in the RV? We have done the research to answer this question in this article.

Typically, most RV's use 1/2 inch PEX lines for the water lines. However, some RVs use a 3/8 inch PEX. The size will depend on your RV in specific.

PEX piping has many benefits; it can still burst at low temperatures meaning you will need to replace it. That's why in this article, we will discuss the standard PEX lines used in RVs. In addition, we will take a look at how to replace RV water lines, so read on!

Water pipes PEX and mounting tools on the table, What Size Water Lines [Including Pex Pipes] Are Used In RVs?

What Size Water Lines (Inc. Pex Pipes) Are Used In RVs?

RV water line sizes are easy to find. However, it is important to know the correct size of water lines for your RV. A majority of modern RV's use PEX tubing and piping because of its several benefits. 

As we say above, there are two standard sizes of PEX used in RVs - 3/8 inch and 1/2 inch. So if you are replacing your lines, make sure you get the proper size to avoid leaks and other issues.

Regarding standard sizes for PEX, the 1/2 inch is the biggest PEX used in RVs, while the 3/8 inch is a slightly smaller size PEX. However, most RVs use 1/2 inch PEX tubing or piping.

1/2 inch PEX tubing or piping is used because it has the highest flow rate. Additionally, if you compare it to copper piping that is the same size, it will have a higher flow rate and flexible ability.

In addition to the ability to be flexible, PEX is also easy to work with. The reason is that you can bend it in different ways without worrying about kinking or breaking the line.

PEX is used in RVs because it is easier to install. In addition, it is a flexible material so that it can bend around corners easily. It is also relatively cheap and easy to find in hardware stores.

Worker connecting alupex pipes with a tap

Cold Areas

If you live in a cold area, be sure to winterize your RV correctly. If you don't and the temperatures drop below zero, the PEX pipes can freeze and expand. While they are less susceptible to bursting than copper, it is still possible.

Lastly, the size of the PEX will depend on your RV. This is because all RVs are different, so the sizes vary depending on the RV itself.

If you have an older RV and don't have PEX piping, you will need to check with the manufacturer for sizing and type. Some old RVs used polybutylene, but it isn't anymore used in the United States.

As a result, it may be harder to find, so if you need to change your water lines, it may be worth switching to PEX piping in your RV. 

Blue Pex Pipe with Open Connector

What is the PEX water line?

PEX is a type of water line that is flexible and made out of plastic. The name is short for cross-linked polyethylene, and while it is easier to work with, it also can handle higher amounts of pressure from the water.

In addition, because Pex water lines are made from plastic, they do not corrode over time as copper piping does. As a result, PEX water lines are designed to last long.

PEX tubing or piping has different manufacturing methods called cross-linking. The cross-linking process involves the material being heated and cooled so that it becomes more flexible. In addition, the material is then stretched out into a flat shape before it is rolled up into a tube or pipe.

How long do PEX pipes last?

PEX pipes have been tested to last 100 years or more. So while you have to replace the copper every few years or decades depending on the climate, PEX will last much longer.

In addition, PEX pipes won't corrode or pit, so they will retain their original form, size, and shape for much longer. It is also resistant to leaks so that you won't worry about constant maintenance.

As with anything in life, there are always some instances where PEX might break or crack. The most common reasons include extreme temperatures, physical damage, and over-tightening. Nonetheless, PEX can expand to three times its size and then return to its original size.

no people, background

Cons of PEX piping

While PEX piping and tubing have several benefits, they have some downfalls. Let's take a look at them below:

Sensitive to UV light -

PEX is sensitive to UV light, so if you leave it outside for a long time, then it might start to break down and crack. As such, always keep your Pex lines covered at all times.

You Can't Install it in high heat areas

Do not install PEX in high heat areas such as near a fireplace or other heat sources because it might deform and become unusable. However, if you want to use it in these areas, you can always purchase self-regulating PEX tubing so it won't become too hot to touch.

It's Semi-Permeable

PEX tubing is semi-permeable. This means that some pores allow water to pass through over time. As such, you can't use it in low flow areas or around plants because they will get dry too quickly.

Increases the risk of freezing

As previously mentioned, Pex pipes are more susceptible to bursting if the temperature drops below zero. In order to prevent this from happening, always winterize your RV correctly and turn off the water supply before going on a trip.

Vulnerable to chemicals

PEX is vulnerable to chemicals such as chlorine. As such, you should always add a filter to your shower or tap in order to remove the harmful chemical from the water supply. While it isn't a requirement, it is still necessary, especially when living near pools and public beaches.

Vulnerable to pests

Pex lines are porous, so they can easily attract pests. As such, you need to ensure that you seal your RV completely or have a pest control service come in every couple of months for prevention purposes.

Leach toxic chemicals

Pex piping does leach toxic chemicals. While it isn't dangerous, it can impact your health and wellness; to prevent any leaching from occurring, ensure that you use a water filter with all of your drinking water.

How Do you Replace RV Water Lines?

Water pipes PEX and mounting tools on the table. Plumbing

  1. The first thing you need to do is buy the correct fittings, tubing, and tools. You can either buy these online or at a local hardware store. Once you have everything ready, turn off the water supply on your faucet.
  2. At this point, make sure that all of your taps are off in order for the water pressure to drop. Once the pressure has dropped, remove the hoses at your water tank and open up the main faucet.
  3. Now you're ready to begin working on your PEX lines. First, look for any kinks or damage in order to make it easier for you to cut off old sections of PEX tubing.
  4. You should also purchase a cutter to remove your old lines and install new ones. Ensure that there aren't any leaks after installation; otherwise, water will drip out and cause problems.
  5. Get your new Pex tubing ready, ensuring that you have the correct measurements and cut them to size. Remember not to connect two pieces of tubing with a connector because it might cause a leak.
  6. Ensure that all of your connections are tight and push the new attachments on tightly. That's all there is to it!
  7. If you don't feel like doing it yourself or run into any problems, call a professional to take care of the job for you or help out.

What are the Red and Blue Hoses Under RV?

The red and blue hoses under your RV are the low point drains. The blue is your cold side, and red is your red. They usually run through your exterior and connect to the sewer drain at the back of your RV.

Final Thoughts

As you can see, there are many different benefits to using Pex tubing. While it might seem complicated at first, once you understand how your RV water system works, then you'll be able to use Pex tubing without any hiccups. If not, consult a professional or break down and buy new fittings for your RV.

If you liked this article, check out our other RV articles:

Do RV Toilets Have A Wax Ring?

Can You Clean An RV Toilet With Bleach?

How To Get Rid Of Sewer Flies In RV Toilets

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