Skip to Content

RV Water Lines: How to Find, Repair, and Seal Leaks

You could face a severe problem if one of your RV water lines springs a leak. We have owned 4 different campers over the years and everyone has had a water line leak at one point or another. You may not fix every issue, but every RV owner should know the basics of RV water leak repair. If you want to protect your RV and wallet from a significant repair, you need to know how to find, fix, and seal any leaks in your RV water lines.

Today, we’ll share some of the basics of addressing these plumbing issues. Let’s get started!

Water Line Leak In RV with floor damage
Yep, that’s the bathroom in one of our RVs. A water line leak behind the toilet caused floor damage.

Where Types of Water Lines Are Used In RV’s?

Water lines in RVs are usually plastic tubing. PEX is the name brand but it could be a number of different types. The size of the lines will vary but 1/2 inch is the most common. Luckily this is the same type of water line used in most modern homes so there are lots of parts and pieces available to fix them these days.

For sewer lines, RV’s almost always use black ABS plastic pipe. This is different from than white PVC that most homes use. ABS is a stronger plastic but in a pinch, PVC can be used in place of ABS but will require special glue to connect the pipes together.

RV water and sewer lines
The red and blue are RV water pines (PEX) and the black tube is ABS

Where Are Water Lines Located In An RV?

RV manufacturers do an excellent job concealing RV water lines when constructing campers. While this may be aesthetically pleasing to buyers, it can complicate some repairs. They’ll run these lines in the RV’s underbelly and behind walls. You may need to remove covers, drawers, or other materials to access them.

Any faucet, toilet, or shower in an RV will have water lines running to it. If you have an outside kitchen or a bathroom at the rear of your RV, water lines will run the length of your rig to deliver water. The water lines in an RV can look like a jumbled mess of various connections as water needs to run to water pumps, heaters, and the multiple faucets, toilets, and showers in an RV.

RV water lines
The water lines in an RV can look like a jumbled mess, but each one serves an important function.

What Are Some Common Causes Of RV Water Line Leaks? 

There are several common causes for an RV water line to leak. If you’ve been around RVs for long, you know that quality craftsmanship isn’t something RV manufacturers typically have.

Sometimes workers hurry when putting together an RV’s plumbing system and do poorly connecting the water lines. In an ideal world, the manufacturer or the RV dealer would catch these during pre-delivery inspections, but that’s not always the case.

Frozen RV pipes and water line leaks can cause major damage to your RV.

When you tow your RV, you’re subjecting it to an earthquake-like experience. Even on a smooth highway, water lines will vibrate and shake, which can cause the fittings that connect the various water lines to come loose. This can cause a slow drip or a much more serious situation. You want your fittings and connections to be tight to help avoid any potential RV water line leaks.

Another typical way that RVs develop leaks in their plumbing systems is through water freezing in the water lines. This is why properly winterizing your RV is crucial if it’s sitting in storage in freezing temperatures. Water expands when it freezes, and while RV water lines can handle some expansion, many of the fittings are less forgiving. The expansion can crack the fittings and cause severe damage before you notice them.

The Best RV Winter Setup: How to RV in Winter and the Gear That Will Keep You Cozy Warm!

Do You Need to Winterize Your RV Water Lines?

Falling temperatures in autumn typically mark the end of the camping season for many RVers. Most campers take the opportunity to do maintenance and prepare their RV for its long winter nap. RV owners in areas where temperatures can drop below freezing must winterize their rig, including their RV water lines.

There are a few ways to winterize your RV water lines. One method is to drain the water system and use an air compressor on a low setting to blow out any remaining water. The other method is to fill the water lines with RV-safe antifreeze to avoid expansion in the fittings or water lines during freezing weather. Don’t forget to drain your waste and water heater tank.

Pro Tip: Use our guide on How to Use RV Antifreeze to Winterize Your Rig to ensure your pipes don’t freeze!

Underside of RV with hose connection
First, identify where your RV’s leak is coming from to best determine how to fix the problem.

How to Repair and Seal Your Leaking RV Water Line 

Once you identify a leak in your RV’s water system, you should locate it as soon as possible. This is not an issue you want to ignore, as these problems do not fix themselves and can cause severe damage to an RV.

Once you locate the location of the leaking water line, you’ll want to fix it. Let’s examine the tools you need and how you can set the leak.

Tools You Need

The best thing about RV plumbing is that it’s not challenging and doesn’t require a tremendous amount of tools to repair. You’ll typically only need a tubing cutter for PEX tubing. This helps ensure you get a smooth and clean cut through the tubing when repairing it.

IWISS iCrimp PEX Pipe Cutters Tool for Cutting...
  • Pex Cutting Tool: Cuts PEX Pipes from 1/8" to 1"
  • Capacity:PPR PEX A pipe cutter is an easy to use, great value...
  • Easy Operation: Its spring-loaded handle opens easily so you can...

In addition to the water line cutters, you’ll need PEX tubing if you need to replace a section of the water line. You’ll also need the appropriate connectors or fittings.

RVs typically use either ⅜-inch or ½-inch tubing for their water lines. Many RVers will replace manufacturers’ low-quality parts to prevent any potential leaks or issues in the future.

We recommend using Shark Bite connectors that you can get at any hardware store. These connectors are super simple to use as all you need to do is push the two pieces of pipe into the fitting as they make a solid connection.

The Process

If you need to do any work on your water lines or the fittings, you’ll want to shut off the water to your RV. Once you shut off the water, go to each of the faucets.

Open them for a second or two to release the pressure in the lines. This can help you avoid a potentially messy situation once you start cutting into your RV’s water lines.

water block in RV
Some very large RVs have a way to shut off individual water lines, if you do not have this then the entire water supply will need to be shut off.

RV manufacturers typically include plenty of extra tubing that allows for minor repairs down the road. Unless you’re replacing a massive chunk of water line, there’s a chance you can cut into the water line and remove the damaged fitting or section of tubing.

If you purchased a quick-connect fitting, you slide the pieces of tubing into each end and ensure you feel them click. It’s that easy!

Once you replace all the sections of the water line or fittings, you’ll want to test the system thoroughly. You don’t want to pack up your tools and put back any removed covers to access the water lines without checking the system.

Turn the water on and wait for the lines to pressurize. Look for signs of dripping or leaks in the system, and turn it off if you discover a leak.

Shark bite fittings in RV
Note the brass fittings in this connection. These are shark bite push-to-connect fittings (see the little shark). You can use rings and a crimper for PEX as well, but for occasional fixes, shark bite is so much easier and removable.

Do You Need Special Water Hoses for Your RV?

While an RV’s water connection will connect to a standard water hose, you should only join a water hose with a design for drinking water. A typical water hose you might use in a garden can release harmful chemicals into your drinking water. 

This can be especially common when the hose heats up while sitting in the hot sun. The heat breaks down the hose and releases the chemicals into your water. A drinking water hose isn’t expensive. You’ll gain the assurance that your drinking water is safer than with a standard hose.

Pro Tip: Need a new water hose? We found the 7 Best Drinking-Safe RV Water Hoses for Fresh Water.

RV Faucets and Filters That Will Effortlessly Save & Purify Water - RV Touch Faucet

Keep Your RV Running Smoothly With a Functional Water Line

Many RVers fear a leak from a busted water line or fitting in their plumbing system. While it’s not ideal, it’s not the end of the world. Anyone with some mechanical skills and a couple of tools can quickly make the necessary repairs to restore the water system in their RV.

You don’t have to haul your RV to the nearest service center or call a mobile technician to address this water leak repair. We’re confident that you can tackle these repairs yourself!

Do you have the necessary tools for an RV plumbing repair? Tell us in the comments!

Become A Mortons On The Move Insider

Join 15,000+ other adventurers to receive educating, entertaining, and inspiring articles about RV Travel Destinations, RV Gear, and Off-Grid Living to jump-start your adventures today!

Also, join our Mortons on the Move Community discussion over on our Discord Server!

About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

About Us

Sharing is caring!

Becky W

Sunday 6th of August 2023

We have a leak behind the cabinets near the fridge. How do you get behind the cabinets? No drawers, just doors

Mortons on the Move

Monday 18th of September 2023

Sometimes you need to start taking things apart, or cut holes :( We have had to cut two holes in cabinets to repair leaks in our RV.

Paul C

Wednesday 26th of October 2022

Unfortunately didn't see the "how to find" part of the article :-(