By Dustin Simpson
One of the most frustrating things for an RVer is having to deal with a water leak underneath the RV in the underbelly area! And if you didn’t know, this is a dreaded repair for any RV technician. From sewer leaks, to dump valve cable failures, water lines, waste tank, gray tank, fresh water tanks, and the hundreds of fittings, all can leak at any time due to use and wear and tear from traveling.
As you will see in the pictures, there is a mess of wires and plumbing that we have to contend with when trying to pinpoint the leak. Underbelly leak repairs can be like looking for a needle in a haystack.
There are several contributing factors that can cause an underbelly leak:
- Supply lines could have been improperly run and were not secured into place.
- Road vibration and flex cause wear and tear/rubbing underneath the unit.
- Normal use of the water pump causes vibration.
- Improper use by not using a water pressure regulator.
Why is this repair such a nightmare?
- On average, there are 200+ water line connections throughout the unit.
- Heat ducting and electrical wiring are often in the way.
- In most cases, we also have to pull LP lines, power/manual leveling jacks and/or Styrofoam around pipes in order to inspect an area and make repairs.
If you are experiencing a leak, there is some helpful information that you can provide that will save your technician some time, which hopefully will also help save your pocketbook:
- Is the leak black, gray or fresh water?
- Is the leak hot or cold water?
- Was the tank overfilled or is it a drain valve leak?
Knowing this information will help locate the leak faster!
Finally, should you end up in a position of needing an underbelly leak repair, whether it is you or an RV technician, this is your excellent opportunity to do the following while the underbelly is removed:
- Add additional insulation.
- Add additional spray foam where needed. This will help seal off any penetration from the floor to the house which will help reduce the interior heat or cooling loss. In addition, this will also help reduce the path of entry for pests, rodents and dust/dirt.
- Secure all water lines and electrical wiring that is floating around to help prevent future leaks.
- Secure and retape all heat ducts and piping.
If you are doing these repairs yourself, here are some links to items you’ll need to complete the job:
- Silver bubble insulation
- Great Stuff black spray foam
- Underbelly Tape
- 6″ zip ties
- Foil tape
- PEX Cinch Tool and Pipe Cutter with clamps.
More from Dustin
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From the factory, the underbelly of our so-called 4-season TT is all one piece other than a small access panel. I dread ever having to do repairs in the underbelly.
Another excellent article, thanks Dustin.
Thank you, Dustin! My, what a mess of wiring and other things in the one picture! I do not envy your techs in that situation. Have a great week and safe travels!
If you suspect issues within the underbelly but dread the need to take down a huge section of underbelly, cut a strategically located hatch large enough to get your head and flashlight into the underbelly. I’ve done this twice on a 10 year old 5th wheel. Assuming the material is thick enough and stiff enough, you can retain the piece you cut out as the hatch. First cut the front facing side of the hatch and attach the hinges across the cut. Then cut out the backside facing side of the hatch and attach a latch across the cut. Then finish the hatch by cutting the two sidewalls. By aligning your hardware this way the hatch is encouraged to stay shut as you drive. Use tape to seal the cuts.