Sunday, December 3, 2023


Motorhome owners: Does your RV sometimes smell like an outhouse while you’re driving?

Mmm… Don’t you love when you’re driving down the road, perhaps during a beautiful sunset, or a nice drive along the coast, when, sniff, sniff, you smell an outhouse-like stench coming from the back of the motorhome? Isn’t that just a wonderful thing?

If you’re a motorhome owner, does this happen to you while you’re driving? It’s a common thing for us motorhome owners to experience. So if you do, know that you’re not alone.

Please tell us in the poll below, and if you have a solution, will you tell us what it is in the comments? Thanks, we appreciate it!

Emily Woodbury
Emily Woodbury
Emily Woodbury is the editor here at She was lucky enough to grow up alongside two traveling parents, one domestically by RV (yep, Chuck Woodbury) and the other for international adventures, and has been lucky to see a great deal of our world (and counting!). She lives near Seattle with her dog and chickens. When she's not cranking out 700+ newsletters for she's hiking, cooking or, well, probably traveling.



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Paul Esterline (@guest_117305)
2 years ago

I used to have that problem. I learned that if you empty your black water holding tank before travel no more stink.

Frank berkey (@guest_117287)
2 years ago

You need to pressurize you cabin with fresh air, too many spaces like TV and boats are taking air out of the bathroom, which a little is good but you need to be forcing air into the space so “smells” don’t go where you don’t want them

Bob Weinfurt (@guest_121637)
2 years ago
Reply to  Frank berkey

You’re absolutely right. I’ve had that issue while driving with the front windows rolled down. My solution was to close all the windows and roof vents but open the vents up front, thereby pressurizing the inside instead of drawing in air through the bathroom.

Last edited 2 years ago by Bob Weinfurt
Neal Davis (@guest_117105)
2 years ago

No, sorry, never have had the problem. Consequently, I have no solution(s) to offer either. 🙁

Pat (@guest_117099)
2 years ago

Siphon 360 solved that problem. Three years full time RVing since installation, and still no odor.

rag_ftw (@guest_117110)
2 years ago
Reply to  Pat

Ditto on the Siphon 360!

Paul (@guest_117092)
2 years ago

We have a roof vent very close to the rooftop sewer vent pipe … we quickly learned to never travel with that rear roof vent open!!

Joe Allen (@guest_117091)
2 years ago

Took a huge sniff a few minutes ago, smells like money!

Danny (@guest_117090)
2 years ago

I put a directional wind device on the roof vent. It actually spins according to the direction of wind causing it to pull the odor into the wind. It looks like the bottom tip of an outboard motor. Never had the smell afterwards and was a great investment. I think it cost about $18

John (@guest_117089)
2 years ago

I put Camco Cyclone rotating vent covers on and never have a problem.

Marc Ornstein (@guest_117085)
2 years ago

What/where are “air admittance valves”?

Bill K. (@guest_117108)
2 years ago
Reply to  Marc Ornstein

They are under each sink. You’ll find them either white or black in color. They are a cap on the end of the pipe.

David Telenko (@guest_117083)
2 years ago

I had that problem in my 1999 Winnebago Adventure. Almost from day one there was a hint of that wonderful odor, seems it got worse when I would open the driver slide window! When I brought it back to get it fixed they replaced all those line vents, etc. even that didn’t make it better, I also changed out the vent on top of the motor home about a year later & that’s where I found the problem, seems they hadn’t put the vent line in the tank. Had to tear stuff apart to get to it. After that the stink went away, but still sometimes when my driver window was open we would get to enjoy the odorific smell, but I started using Happy Camper in the tank & that fixed it.

Jim (@guest_117082)
2 years ago

No. Black tank maintenance, black tank maintenance.

Roy Davis (@guest_117100)
2 years ago
Reply to  Jim

You nailed it!

GeorgeB (@guest_117078)
2 years ago

Just once and it was my fault leaving the black tank too full prior to traveling home after a NASCAR race. Never doing that again as well as a fancy new vent cap fixed the problem.

Last edited 2 years ago by GeorgeB
dan (@guest_117070)
2 years ago

We replaced the vent cap a few years ago, but only because it finally turned to dust and left pieces in the driveway. Otherwise, we keep the windows open frequently. When it’s closed up in storage we use just use air fresheners. Now that I said that out loud watch my plumbing fail.

Vic (@guest_117069)
2 years ago

Changed out the vent caps as others said, that mostly solved. Occasionally the toilet flush valve gunk’s up and won’t hold water, if we need to travel a plastic bag with water makes a good temporary seal until we get it cleaned.

Joe (@guest_117063)
2 years ago

The only time we had a problem is after having a toilet replaced under warranty and the technician did not install the seal. We travel with as little liquid in the tanks and it also splashed out onto the floor, what a mess.

Stephen Florie (@guest_117061)
2 years ago

As others said, I changed the air admittance valves which helped, then I replaced the vent cap with the Camco Cyclone rotating vent cover which took care of the problem.

David Walczak (@guest_117057)
2 years ago

Like Ed K, I used to have a problem. It wouldn’t always happen, but when it did, it was a bit funky. To solve the problem, I installed the 360 siphon caps. Helped, but we still had a smell on occasion. Next, I changed out all the air admittance valves. There was no real change.

After poking around, I found what appears to be micro-sized cracks on the inside bend of the flexible waste line running from the sink to the gray tank. I removed it and, when I flexed the pipe, the cracks grew in size. I replaced the hose (it’s a 2-inch flexible spa hose), and we haven’t had any more problems!

I should mention that our sink is in one of our slides. Hence the reason for the flexible drain line.

Tom (@guest_117055)
2 years ago

2nd vote for the Siphon 360 Vent Cap.

Ed K (@guest_117052)
2 years ago

Use to until I did two things. First I replaced the Air Admittance Valves on the sinks and this helped a lot though not 100%. The following year I installed the Siphon 360 Vent cap and have not had any smell since. I was one of the first to get the siphon 360 and 100% recommend it. Been working for the last several years with no issues.

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