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Your RV Toilet STINKS! Learn How to Eliminate RV Toilet Odors

Your RV Toilet STINKS! Learn How to Eliminate RV Toilet Odors

No, you shouldn’t smell your RV toilet. That’s not normal. While an RV toilet doesn’t work in quite the same way as a toilet in a sticks & bricks house, that doesn’t mean it should smell. So, if your RV toilet stinks, it’s time to learn how to eliminate RV toilet odors.

How Does an RV Toilet Work?

This is actually a mystery to people who’ve never traveled in an RV. How an RV toilet operates, flushes, and where the “stuff” goes are burning questions in the minds of non-RVers everywhere.

Okay, so maybe that’s a tad dramatic but, in truth, RVers are asked questions about how their RV toilet works all the time.

There are actually a few different types of RV toilets, and you can learn more about each of them in our post called “The RV Toilet Talk” (or you can watch the video embedded here):

For the purposes of today’s post, however, we’re talking about a traditional gravity flush RV toilet that uses water to flush waste into a holding tank.

A gravity flush toilet looks very similar to the toilet you’d be likely to find in a home. There are some functional differences though.

First, a gravity flush RV toilet has very little water in the bowl – usually just enough to cover the seal. It also most often has a foot pedal for flushing (some RV toilets may have a push-button flushing mechanism, though this is less common). Either way, a very small amount of water stays in the toilet bowl after flushing, covering the closed valve/flap and helping to create a seal to keep odors in the black tank.

When you flush a gravity flush RV toilet by depressing the foot pedal, the flap opens and the contents of the toilet drop into a holding tank that sits beneath it. This is your RV black water tank or wastewater tank.

When you depress the foot pedal, a valve is opened that allows water to enter the toilet bowl, helping to rinse down the sides of the bowl to leave it fresh and ready for use.

The sewage collects in your black tank, and the tank eventually needs to be emptied, as shown in our “RV Holding Tank Dumping 1-2-3” video:

Why Does My RV Toilet Stink?

Let’s reiterate… your RV toilet shouldn’t emit much, if any, smell at all. If your RV toilet stinks, you’ve got an issue to resolve related to any one of several components in your rig.

Let’s take a look at each of the possible reasons why your RV toilet might stink, and how to resolve each to eliminate those nasty RV toilet odors.

The toilet bowl seal/gasket is no longer sealing properly.

If this is your problem, it’s very likely that your RV toilet bowl isn’t holding water as it once did.

The water that’s retained in the bottom of the bowl is key to helping seal out any odors from your black tank. If your RV toilet doesn’t retain that small puddle of water in the bowl between flushes, then the toilet seal/flap seal is leaking. This can happen if the seal dries out or with age.

If your RV toilet stinks most right down inside the bowl itself, and there’s no water in the bottom of the bowl, you’re actually smelling the black tank right up through the toilet.

If the seal is no longer holding water in the bowl properly, it may need to be replaced, though you can try lubricating the seal with a bit of plumber’s grease (non-petroleum base) or a product like this:

Thetford RV Toilet Seal Lube and Conditioner - Toilet Seal Lubricant - 24 oz 36663
  • [VERSATILITY]: Thetford's RV Toilet Seal Lube & Conditioner works with all permanent or portable toilets found in RVs and boats
  • [FUNCTIONALITY]: Penetrates the toilet seal, lubricating and protecting

How to eliminate the RV toilet odor:

If this seal appears to be the most likely culprit, you can replace the seal as a DIY project on most RV toilets. Be sure to purchase the seal that works with your particular make/model of RV toilet.

385311462 RV Toilet Rubber Bowl Leak Seal Kit Replace For Dometic Compatible For Dometic / Sealand / Mansfield / VacuFlush and Travel Trailer RV Camper Toilet
  • Does NOT Compatible with 300, 310, 320 series Dometic toilets
  • Replacement for Dometic 385311462 & 385316140

The toilet flange seal is no longer sealing properly.

Just like the toilet in a sticks & bricks house, your RV toilet has a floor flange seal that sits between the floor and your RV toilet’s pedestal. It could either be a wax seal or a rubber seal. Either way, it can eventually age and thus fail to seal properly. If that’s happened to your toilet, this could be the source of your RV toilet odor.

How to eliminate the odor:

Replace the toilet flange seal. Be sure to buy the correct toilet flange seal for your RV toilet. If you need them, you can get detailed instructions on how to remove and replace your existing RV toilet flange seal.

Here’s a toilet flange seal for popular Dometic toilet models (300/310/320):

RV Toilet Seal Replacement for Dometic 300/310/320 Toilet, RV Toilet Gasket Parts Flange Seal Kit
  • 【Package includes】The Package includes 1 x black seal, 2 x brass T-screw, 2 x stainless steel nut, 2 x stainless steel washer, 2 x bolt cover. The...
  • 【Designed for 300 Series RV Toilet】Perfect compatible Dometic 320, 310, 300 Models RV, motorhome, and trailer toilets. Does not fit 210, 510 or...

While you’re here inspecting the seal, check to be sure that none of the mounting hardware has cracked, either.

The black tank vent pipe is blocked.

Proper airflow up and out through your RV’s black tank vent pipe is important to helping to ensure odors don’t enter your RV. When functioning properly, the black tank vent should help to create a flow of air up and out onto the roof, so that when you flush the toilet, air will tend to flow down into the tank and not back up and out. But if the vent pipe is blocked you could experience sewage odors inside (or outside) your RV.

Your RV’s black tank vent pipe can become clogged by debris that has fallen from trees, etc., or by a nest made by bees or other insects (not at all unusual).

How to eliminate the odor:

If your vent pipe is clogged, you’ll need to head up to your RV’s roof to see what’s what. You should be able to dislodge most clogs by removing the vent cap and using a brush or wire to clean out the vent stack.

Be cautious here – it’s possible that bees have made a nest in this area and you don’t want to be up on a ladder angering a nest full of bees!

Another possible issue related to your black tank’s vent pipe is that the vent pipe cover/cap may be a design that causes it to channel wind/air down and into the tank, pressurizing it so the odor is entering the RV.

The solution to this is to replace the vent pipe cover/cap with a 360 Siphon Vent to ensure that any outside air movement/wind is creating airflow up and out of the tank, instead of down and into it.

Lippert 360 Siphon RV Roof Vent Cap for Odor Prevention with Universal Fit, Built-In Bug Screen, White Polycarbonate - 389381
  • Eliminates Odor - Exhausts Odors Out The Roof Vent Before They Have A Chance To Invade Your Rv
  • Compatibility - Engineered For A Universal Fit, The 360 Siphon Is Compatible With All Rv Vent Caps

Here’s our video showing how we replaced our holding tank vent pipe caps with 360 Siphon Vents (the new units have an improved installation procedure, but this will give you a good idea):

The sewer pipe/hose is leaking.

If your sewer hose is leaking, you’ll definitely smell sewage. You’ll either find this out when you’re at a dump station, or you’ll smell the sewage when you’re connected to a full hook-up at a campground or RV park.

You’ll know that this is your issue if you notice the smell when you’re outside the RV more than in. Or if you can tell it’s coming in an open window on the sewer hook-up side of your RV. Either way, if this is your issue it needs to be rectified immediately.

How to eliminate the RV toilet odor:

Replace the sewer hose. It’s best to buy a high-quality sewer hose to prevent leaks and messy perforations from occurring. No one wants to deal with a leaking sewer hose! We’ve got a post on the best RV sewer hoses, and here’s the sewer hose that we’ve been using for our almost 20 years on the road:


If you need to replace your sewer hose, be sure to check out our post on how to set up a new sewer hose the easy way!

The black tank is cracked/leaking.

Here again, if your black tank is cracked or leaking, you’ll likely find the strongest smell of sewage outside your RV, though on any RV where the holding tanks are enclosed within the structure of the rig, that odor could easily find its way inside, too.

How to eliminate the odor:

The only way to deal with this issue is to have the black tank repaired. You may be able to undertake this atrocious unpopular task depending on the location and extent of the damage, or it may require a professional repair.

Small cracks/leaks may be repairable (at least temporarily) with Eternabond tape or a plastic-weld epoxy. But, depending on where the crack/leak is located, you may need to remove the entire tank to get to it… at which point, it may be best to replace the whole thing (if available).

The black tank is clogged.

If your black tank is clogged, you may start to experience RV toilet odors inside your RV. Improper draining when dumping can result in the accumulation of solid matter in the tank. AS that material increases in volume, the odor emanating from it is likely to increase, too.

How to eliminate the RV toilet odor:

If this is your issue, you’ll need to tend to the task of thoroughly dumping and cleaning your RV black tank right away.

If you’re so equipped, you’ll also want to use your RV black tank flush to clean everything out as thoroughly as possible. If cleaning out your own black tank doesn’t do the trick, you may need to have what we call an RV Colonoscopy performed!

The weather is very hot.

Very hot weather can increase the rate of growth of odor-causing bacteria in an RV black tank. The more bacteria there is to digest, the more gasses are produced. Increased gas production means more odor. During hot weather is the most common time for RVers to say “My RV toilet stinks!” even if they don’t normally experience the problem.

How to eliminate the odor:

The best way to address odors from hot weather (and just generally) is to use a really good holding tank treatment to break down the waste in both the black and gray tanks. This keeps your holding tanks cleaner and running smoothly.

One scoop in the black tank and one in the gray tank are typically all you need. But if temperatures in your area are very high, you may want to use a second dose.

There is a variety of holding tank treatment products on the market, but after a couple of decades of full-timing, our favorite product to use is a non-chemical organic treatment called Happy Campers.

Happy Campers RV Toilet Treatment 18 - Extra Strength Odor Eliminator for Black and Gray Holding Tanks
  • Powerful Odor Control: Say goodbye to unpleasant odors with our powerful formula that neutralizes and eliminates foul smells, leaving your RV smelling...
  • Effective Waste Digestion: Happy Campers breaks down waste and toilet paper quickly and efficiently, preventing clogs and ensuring smooth tank...

The original Happy Campers, when used on a regular basis, really does help to keep significant issues at bay, but Happy Campers also makes an “extreme” treatment product for deeper cleaning.

If you’re having issues with odor and with your tank sensors not working well, you may want to consider trying this treatment.

Happy Campers Extreme RV Holding Tank Cleaner
  • Super cleans RV holding tanks
  • Sensors: Restore poor working sensors

Bonus Tip: If your tank sensors aren’t working well, here are four ways to clean your RV tank sensors.

You’re leaving the roof vent fan on when flushing the toilet.

If your RV toilet stinks only when you flush it, this might be the problem… If your RV is equipped with a vent fan in the same room as the toilet, leaving it open & running when you flush the toilet can be a problem. That fan may be able to overcome your blank tank vent’s ability to create an updraft out of the tank… so, instead of air naturally tending to go DOWN the toilet as you flush, the running vent fan may be suctioning air (and odor) UP and OUT of the tank. If this is the issue, you’ll know it right away… as you’ll likely get quite a nose full when you flush.

How to eliminate the RV toilet odor:

Simple. Don’t do that. ????????????????

How Should I Clean My RV Toilet?

Regularly and thoroughly! However, you want to avoid using harsh or abrasive cleaners on your RV toilet. These can damage the bowl, blade valve, and seal – none of which you want to do.

You can use equal parts vinegar & water, or a dedicated RV toilet bowl cleaner like these:

Unique RV Toilet Bowl Cleaner and Black Holding Tank Enhancer Liquid, Squirt-Top Dispenser, Cleans All Toilet Types (24 oz.) 41F-1az
  • Cleans RV toilet bowls. Specifically designed for RV and marine toilets. Cleans your toilet bowl without compromising the break-down process in your...
  • Removed tough stains, toilet bowl rings and urine smells from plastic, ceramic, and porcelain toilet bowls. Won't damage seals or valves. Helps...

No products found.

We answer all your questions about cleaning your RV toilet, including “Can I use household toilet bowl cleaner in my RV toilet?” in a post dedicated to exactly that.

Enjoy Your Stink-Free RV Toilet!

Now that you’ve identified (and resolved!) the source of the odor causing your RV toilet to stink, you can get back to having fun and won’t be embarrassed when guests visit you on board your rig. We hope these tips enable you to banish the words “My RV toilet stinks!” from your vocabulary permanently!

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Wednesday 10th of April 2024

You missed one. Namely a loose connection between ceramic bowl and plastic pedestal base on Dometic 310, a very common toilet. The 4 bolts rust out, or the nylon fasteners get brittle and break. The effect is allowing toilet water to leak into the pedestal, even filling it. Then the floor can begin to rot out. Fortunately someone created a repair kit (not available from Dometic) on eBay.

Marc Goldstone

Saturday 8th of April 2023

My Sportscoach 339DS Diesel Pusher had sewer odor that for two tears we couldn't pin down. The odor was present when we dumped especially when using the black tank flush connection. Forest River was of no help.

I peered into an access port in the shower and was able to see a black PVC vent pipe but couldn't determine where or if it was connected to a roof vent which is required by the RVIA which are like building codes for a sticks and brick home. I had "assumed" (makes an ass of you and me) that the exising roof vent was connected to both the black and gray tanks. I cut out the back of the spice cabinet near the cieling above where I spotted the vent pipe. I found the 1-1/2" vent pipe was open and not connected to a roof vent!

I drilled a pilot hole through the roof directly above the vewnt pipe and drilled a 2" diameter hole from the roof downward. Completed the unfinished installation and added a roof vent.

We no longer get any sewer odor! The Forest River people have no intention of notifing other owners of the 339DS model even though several YouTube videos for differnet model years show only one roof vent, though if customers complain they may have dealerships do the repair at no cost, but only for those that complain!!!

Forest river refused to reimburse me fo the materials and tools I had to purchase to effect the repair. I am a firm believer in the $200 and two hour rule... better to fix it yourself especially when needing to drive 200 miles roundtrip to the nearest dealership.

Jeff Valloric

Saturday 8th of April 2023

My trailer had odor issues and I checked the toilet tank vent on the roof. The factory had run it's pipe long and the vent cap was only 1/2 inch from the cap....too complicate the issue the hole they cut to run the pipe was 3/4 inch wider than the pipe which allows tank fumes to enter the trailer in the gap. I cut the pipe shorter and added foam filler in the extra space and then used dicor lap sealant over the foam. No more fumes when driving, wind blowing,, vent fans running... Id guess a standard installation procedure at the factory for all RV's easier and cheaper than doing it right.

Mike Compton

Saturday 9th of July 2022

Before our last trip I replaced the seal on our toilet but didn't use the Dometic brand. The replacement seemed to work fine until we came home. There was a couple of inches of dirty, smelly water in the bowl. We did empty before leaving the campground and added a couple of gallons of fresh water. Is this most likely the seal or something we need to have someone look at?


Saturday 9th of July 2022

Hi Mike. Sorry to hear about your troubles... nothing's worse than problems with the toilet, black tank, or both! It's definitely possible that the non-Dometic-brand seal isn't sealing correctly, but what's weird (and seemingly inexplicable to us) is how you could have dirty, smelly water in the toilet bowl if the black tank had been emptied and only had a few gallons of water put back in it. Unless you were driving on unpaved 4x4 roads down the side of a mountain, we can't imagine how the black water could come back up into the toilet, even with an incomplete seal.

Normally, if a toilet seal fails, you know because the water left in the bowl (to help maintain the seal) drains out... and then odors come back up from the tank. Not actual contents from the black tank.

The only other thing we can think is that your black tank got clogged and when you dumped it at the campground, it didn't actually drain completely. Then, adding back a couple of gallons of fresh water brought the level up high enough in the tank that it could slosh up and come through the toilet seal. But, again, if that seal wasn't sealing properly and could allow water from the tank UP into the bowl, that water would have drained back OUT, too.

We'd start by dumping the black tank again and then using a flashlight to carefully look down into the black tank through the toilet valve. See if there's still anything there, which would confirm that the outlet from the black tank is clogged and not allowing it to drain/dump completely. If that's the case, you'll need to try adding something like Happy Camper Extreme or Unique Sensor Cleaner to try and dissolve any waste or toilet paper that's clogging the black tank outlet. It can be a real struggle... and you may want to hire a professional, instead, since it's not a fun project to deal with if that's what's wrong.

Hope it's something simple and you can identify the cause! Please let us know what you discover, or ask more questions if none of the above helps!

Dr. Mike

Tuesday 12th of April 2022

We get the foul oder in our coach, but only when the A/C is on. No A/C….no oder. What makes it more interesting, even after power washing the black tank, the smell still persists (with the A/C on).

Question to you or the audience: How do you power wash the grey tank?

Marc Goldstone

Saturday 8th of April 2023

@Dr. Mike,

Sounds like your AC is leaking cool air to the outside. (like turning on an exhause fan whioch will draw nasty fumes into the coach when the toilet is being flushed)


Thursday 14th of April 2022

Hi Mike! Here's how we got both of our holding tanks power washed:

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