Mysterious Water Accumulation: Water in the RV Belly

posted in: RV | 2

The other evening, we were having dinner with some friends at their RV. What came up in conversation was quite interesting . . . there was a mysterious accumulation of water in the RV belly.

The conversation went something like this:

“Champ’s* not a boy . . . we think she’s pregnant!” *Champ

“WHAT?! Pregnant, what are you talking about?”

“Her belly got all bloated, then her water broke.”

“That sounds serious, let’s take a look.”


Sure enough, the belly of their RV was a bit swollen with some water slowly leaking out. So many questions came to mind:

  • Where is this water coming from?
  • What caused this?
  • How do we find out?
  • How do we fix it?

We went back inside and conversation ebbed and flowed around several different topics. It was while we were leaving that I brought up our condolences in regard to Champ’s water accumulation, and wished them the best.

Seeing how their rig is still under warranty, they were awaiting a professional to diagnose and fix the issue in the next couple of days. They would keep us posted.


Why is there Water in RV Belly


24-hours later . . . I too noticed a distended underbelly on our rig. What is going on, is there a wave of RV pregnancies sweeping through the area?

Not one to be dissuaded by the unknown, I grabbed a drill and removed the front half of our RVs underbelly covering (it is really just a huge sheet of corrugated plastic).

Coroplast sheet from Water in RV Belly post on The Uncommon Road
This fancy corrugated, plastic thingy is actually called coroplast . . . BOOM!


Some water spilled out as I began to remove the screws. Yes, I checked . . . it was clear, odorless, and tasteless (kidding, totally kidding . . . I wasn’t going to go that far).

I took a quick break for a little Google-Fu, and came up with plenty of possibilities of where the water in the RVs belly may have come from:

  • Loose fitting
  • Broken water line
  • Leaky seal
  • Rain water from road
  • The list goes on and on . . .

Armed with my newfound interweb knowledge, I dove back under to see what I could fine.


Behind the Curtain of an RV Underbelly


With everything exposed, I began checking all the fittings. And let me tell you . . . there are a crap-ton of waterlines in this 36’ box.

Water in RV Belly image of multiple water lines in RV underbelly
Yeah, all be spending the next few years mapping these guys.


After checking every visible waterline and fitting, I only found one possibility. The fitting to the flush nozzle for the black tank was somewhat loose. Not drastic, but I gave it a solid 3/4 turn with my fingers before grabbing some channel locks to snug it another 1/2 turn.

Image of RV flush nozzle from Water in RV Belly

With nothing else to inspect below, we began testing all the water sources:

  • Run the cold water in the bedroom sink (nothing)
  • Check the hot water in the bedroom sink (nothing)
  • Turn on the cold water in the shower (nothing)
  • Run the hot water in the shower (nothing)
  • Cycle the washing machine cold/hot (nothing/nothing)
  • You get the point

So now I was at a loss. I may have fixed the issue with the flush nozzle, but didn’t know for sure. There is also the slight possibility certain fact that I overfilled the freshwater tank a few days earlier (oops).


A Little Tidying in the RVs Belly


Not one to let an opportunity slip by, I figured I’d make the most of spending half a day underneath the RV.

First up was the wiring. When I pulled the pan (don’t really know if that’s the right term for the plastic sheet) off, there were quite a few wires just dangling there.

Image of RV wires before and after they are organized.

Easy fix, I just took several zip ties and bundled things nicely. Also, to keep from hanging down in the even I pull the pan again, I tucked them nicely along the frame.


A Little Prevention


Next up was a little bit of prevention. If you spend any amount of time in any of the FB groups focused on RVing, then you probably heard a tale of woe in regard to rodent infiltration (if not, read this thread).

Seeing how RV manufactures like to cut 3” holes to run ½” water lines, there were plenty of orifices that would make entry into our RV easy for an enterprising rodent.

The solution is pretty simple, feel free to use without having to attribute my genius:

  • Stuff holes with steel wool-critters won’t want to chew through it
  • Fill above (just push nozzle through steel wool) and below with that spray foam stuff
  • Celebrate your moral victory over these foul vermin

Side note: While under there I did notice old evidence in the form or mouse (or some other small critter) droppings. Seeing how we bought a rig that was five years old, it was already exposed to environs where this very thing could happen.

  • Follow-up side note: It made the celebration that much sweeter knowing that this horrible rodent infestation rumor was actually validated.


What Next?


Well, we may or may not have found the source of the bit of water that accumulated in our RV’s belly. We had also had several days of strong rains, so that could have been a contributor as well. No matter, we’ll keep an eye on things and keep you posted of any relapse.

The plus side of things is that I learned a ton about what is going on in the underneath area of our rig. I always find it comforting when I can take something apart, see how it works, and the successfully put it back together again.

So . . . there we have it, right there, the case of the mysterious water in the RV belly.

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2 Responses

  1. Leo

    We had a mystery leak…found it to be a cracked drain pipe. This was where the tub and kitchen sink combined to drain into the gray tank. I had looked there several times but it wasn’t until I layed on the floor did I notice the offset pieces. Good luck!

    • Lou

      Hey Leo,
      Glad to hear we’re not the only ones to have experienced this. I’ll keep that drain thing in mind. Figure I’ll periodically check to see if it really is a continuous issue. Will keep you posted.

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