Why does my RV’s toilet smell? Here’s five reasons!

You’re meticulous about keeping your RV clean. Trash is emptied regularly and immediately if you even start to smell anything from it. You tend not to cook food that has a strong odor, such as fish, in your RV. Dishes are washed quickly before left-on food has a chance to start making a stink. And you ALWAYS use that onboard tank sprayer when you empty your black holding tank.

So why do things still smell in your RV? There are five surprising reasons that are causing all the stink.

A dirty toilet

Okay, we admit this one seems pretty obvious and it’s an easy fix. RV toilets, especially the plastic ones (a great opportunity to upgrade to a porcelain toilet!), “hold” onto smells. The longer you wait to clean the toilet, the more stink it’ll hold onto until eventually, the smell fills the entire RV.

Fortunately, this is super easy to fix. A simple cleaning with an antiseptic bathroom wipe should get rid of the smell in no time. Just be sure you get every nook and cranny. Be sure NOT to toss the used wipe(s) down the toilet — dispose of them in the garbage. Otherwise, you’ll soon have a….

Clogged black tank

It’s a common problem and almost every RVer has it at one time or another. If you have a clogged tank, it won’t dump completely—or at all, sometimes—meaning you’re left with old sewage hanging out in your tank for days, weeks, or even months on end. Obviously, this isn’t going to start smelling any better anytime soon. Therefore, you’re going to have to address the clog.

Usually, a clog is caused by too much toilet paper and not enough water. Sometimes this means you aren’t flushing long enough; other times it’s because the dump valve was left open, allowing all liquids to leave the tank and leaving just the solids behind. A leaky black tank can also cause this same issue. Of course, it could also be caused by something being flushed that should not have been (the aforementioned wipes, for instance).

Many RVers will attempt to get rid of clogs in either three ways:

  1. Dump a bag of ice down the toilet. We’ve written before why this doesn’t work.
  2. Dump a huge amount of chemicals, enzymes, etc. down into the tank. Again, here’s why that doesn’t work.
  3. Get a professional to clean your tank’s clog and clean out the tank. Yes, that does works. Every time.

A clogged vent pipe

Sometimes the problem isn’t a clog in your tank, but rather a clog in the vent pipe.

Every RV has a vertical pipe from the black tank to the roof, allowing gases from the tank to escape. If this vent becomes clogged, those gases can’t escape through the roof, and will instead come up out of the toilet when you flush. As you might imagine, this does not smell good.

To check a vent pipe for clogs and get rid of anything that could be obstructing the airflow, simply put a garden hose into the top of the pipe and run some water through it. Be careful when you’re up on the roof.

Bad toilet flange or bowl seal

It’s also possible that your toilet needs a new flange or bowl seal. Both of these seals have a tendency to become worn over time, something that can cause bad RV toilet smells.

If you notice that your toilet bowl won’t hold water, it’s likely that you have a bad seal that is also allowing stinky black tank smells into the RV. Yuck! Meanwhile, a leak around the bottom of the toilet would indicate a worn gasket that could be letting smells in. Also yuck!

Tanks with heavy buildup

Most of the time, an RV toilet stinks because of buildup in the black tank. This might be a large buildup of solids on the bottom of the tank or just buildup along the walls of the tank from regular use. And while using that onboard tank sprayer can help, there’s no way that it alone can prevent this common problem.

As with clogs, solid buildups tend to be caused by too many solids and not enough liquid in the tank. This can be avoided by keeping your dump valve closed, ensuring your tank doesn’t leak, using plenty of water when flushing, and “priming” the tanks after each emptying.

Unfortunately, general buildup on the walls and bottom of the tank cannot be avoided. Instead, walls must be cleaned regularly by a professional tank cleaning service in order to avoid a stink.

How to keep your RV toilet from smelling

Clearly, you won’t want those smells to return once you get rid of them. Fortunately, it’s easy enough to avoid RV toilet smells. If you’re wondering how to keep your RV toilet from smelling, just keep up with your toilet and tank maintenance and you’ll be golden.

Regular, annual professional tank cleanings and stopping the use of tank additives that turn tank contents into sticky, stinky messes are musts. If you’re still having problems or have any questions, be sure to ask us!

Jim Tome, Owner

Jim Tome, Owner

Hi, I'm Jim Tome and, along with my wife, Debbie, the owners of Kleen Tank LLC, the national leader in RV holding tank cleaning service. We've been RVers like you since 2004 and have traveled all over the U.S. in our Airstream travel trailer. We started the business about twelve years ago and have cleaned tens of thousands holding tanks in thousands of RVs. From tiny weekend travel trailers to monstrous fifth wheels to luxurious motorhomes, I've seen just about every situation there is with RV holding tanks and waste systems. I hope you enjoy our articles; I try to post at least one per week and we've got a great library of them to cover just about every problem. Enjoy!


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