Why does my RV smell like sewer? Owning a self-contained RV means having to deal with a few odor issues. Photo: Grand Canyon National Park
Grand Canyon Desert View Campground 03469 by Grand Canyon National Park is licensed under CC BY 2.0
Here’s What To Do When Your RV Smells Like Sewer
Unlike a house where the toilet, shower, and sink detritus can be flushed or washed far and away, an RV carries its waste around inside its belly, sometimes for days or weeks at a time. During this time, odors from whatever went down the drain can creep back up into the RV living space. This makes for some unpleasant conditions on an otherwise pleasant trip.
An RV grey tank is usually the less likely culprit when it comes to smells. The grey tank is the holder of water from sinks and showers. However, soap scum, hair, food waste, and a moist environment can release moldy odors from the grey tank or sinks into the RV.
The best way to get rid of a grey tank smell is to make sure that no food goes down the kitchen sink, use a holding tank treatment, and regularly empty the tank at a dump station.
But what if there are still lingering odors? Why does my RV smell like sewer?
The main culprit of sewage odors will be your RV black tank.
The smell that needs to be dealt with immediately is the stink caused by a much worse effluent. If you are going to use your RV toilet for both Number 1 and Number 2, knowing how to clean out and maintain your black tank is an essential RV skill.
An RV black tank is usually located in the underbelly of the RV. It contains water, waste, and toilet paper from an RV toilet. Emptying and maintaining a black tank is probably one of the most dreaded jobs of any new (or veteran) RV owner.
Don’t worry. Once you take a little time and get the hang of it, making sure the tank is healthy should keep any odors away from your RV life. The tips below should help. Consequently, if you have a smaller RV that combines the grey and black tank into one, you can also follow these tips below.
1. Prevent RV tank clogs
Preventing any clogs is the first step to maintaining a healthy tank. The best way to do this is to avoid putting anything but RV-safe toilet paper down the toilet. If you can handle it, don’t even put your toilet paper down the toilet at all. Instead, do what they do in areas with sensitive plumbing and put it in the garbage.
If you do have a clog, this excellent post by Camp Addict has a step-by-step process to clean out the tank from the dreaded pipe clog or the poop pyramid.
2. Keep plenty of water in the tank
Preventing tank clogs and odors will go much smoother if the black tank always has plenty of water in it. Waste from the toilet needs to be mixed with fluids so that the tank and the solids within it don’t dry out and cause odors. There are several ways to do this.
One way is to make sure to flush after each use of the RV toilet. Adding a little more water down the toilet drain is also useful if your…um…deposit was generous. In addition, the rule of thumb for adding water into the tank is to make sure that the bottom of the tank is completely covered with water. You can monitor this on your black tank sensor or make sure you flush down about four to six tanks of fresh water from the toilet.
3. Empty the tank before it gets full
To avoid odors even further, make sure that when you empty your black tank, you do it before it gets full. This will require another monitoring of the black tank sensor. You should plan to dump your tank at around the 3/4 full mark since this will allow for one or two extra flushes before the tank actually fills to the brim.
At the time you are dumping the black tank, this is also a good time to do a good, if not thorough, clean of the tank. This excellent video by RVgeeks shows not only how to empty and scrub out a black tank, but also how to do a “sniff test” using your bathroom vent fan:
4. Regularly clean and maintain the toilet gate valve
There is really only one simple part that keeps odors from wafting up into your RV bathroom and that’s the RV toilet gate valve. It’s imperative to keep this valve (or flapper) clean and in good repair. The seal around the valve is also an important part in that it holds a small amount of water at the bottom of the toilet. This water will hold back any smells that linger in the toilet or the tank.
If the toilet gate valve is dirty, it may not close and keep that seal tight. Take a wet rag and thoroughly wipe around and under the valve to remove any debris. This is also a good time to check the valve seal for cracks.
5. Keep your tank’s gut happy
Just like your tummy, your tank is happier when full of enzymes. One of the best products for both tank treatment and odor control is Happy Campers RV Holding Tank Treatment. The treatment is a blend of minerals and micronutrients that both treats waste and eliminates odors without perfumes. One scoop will work for a 40-gallon black tank, and the product will also work fine in your grey water tank.
Hopefully, this article helps you answer the question, “Why does my RV smell like sewer?” Make sure you keep track of all your RV maintenance and repairs with an online tool such as RV LIFE Maintenance. Not only can you keep all of your documents in one place, but you’ll also receive timely reminders when maintenance is due to help you avoid costly repairs and potentially serious accidents.
Related articles:
- How To Get Rid Of Awful Black Tank Smells
- 5 Weird Smells In Your RV And What They Might Be
- Avoid A Mess: Empty Your Waste Tanks Cleanly & Easily
Christina is a writer and designer who has written about camping, tiny houses, and alternative living since 2008. She recently traded in her teardrop trailer for a 13-foot fiberglass trailer from 1982.
Most important is to make sure your exhaust fan above your toilet is not running when you flush.
A very important reason that your rv smells like a stinky sewer. You may have a propane leak. It smells like a sewer. It happened to us! Very dangerous.
I usually drain a small amount from the grey tank after connecting the drain hose before dumping the black tank just in case the connections leak or the hose became damaged since the last time that I used it. After confirming no leaks I dump the black tank, grey tank, rinse the hose, and then store the hose for travel.
A 3/4 hose will dump approx 5 gallons a minute, dump and add water to the empty black tank. I add about 3 minutes or 15 gallons and that sloshes while I drive to the next RV park. Repeat every time you dump and you will never have a a tank issue.
We notice tank smell after traveling once in a while. Run the sinks and shower to fill the pee traps and the smell goes away. Probably caused by road movement sloshing the pee traps dry?
I use DAWN dish soap about a capful in the black tank at the beginning of each trip. It makes “things” slippery to drain out of the RV very nicely and it soap so cleans as well.
Our trailer started smelling like sewage and finally found the toilet had a runner seal that had worn out and replacing it fixed the problem. Even our trailer manufacturer didn’t think there was a seal that could be replaced.
Oops. Rubber seal.
I mean rubber seal, not runner seal!
No one has ever explained why toilet paper should not go down the toilet. I was involved with wastewater treatment for most of my career and can’t imagine why. We have had situations where large quantities of paper had to go in the toilet. I’m amazed at the amount of paper that we go through (and I don’t ask). Yet we have never had a problem. And that’s with 3 or 4 elbows between the tank and gate valve. I add 5 – 7 gallons of water to the tank plus Happy Campers prior to using the toilet. It’s a 45 gallon tank.
The number one reason black tank odors get into the RV living space is because one of the sink traps has been sucked dry. A trap holds water making a seal from the living space side of the trap and where the waste is stored. This is true for a regular house and an RV. Most RV toilet spaces have a small sink. Unlike most sinks in the RV that drain into the grey tank, the one in the toilet compartment drains into the black tank. Sometimes this is because it is easier to plumb that sink to the black tank but more likely, it is a way to add water to the black tank to prevent solidification of the waste. Driving down the road sometimes creates a vacuum in the toilet compartment that will suck the sink trap dry. Supposably, there is a “vacuum breaker” that prevents that. Nevertheless, just run some water into the sink to restore the trap water and 9 times out of 10, the offensive odors will stop.
My 2021 Forest River Sportscoach 339DS has sewer odors after dumping, and while changing elevation while traveling. For the first two years I complained about this. I discoverted that the black tank vent pipe had been left open inside a wall between the shower and spice cabinet and it was not connected to a roof vent.
I had to cut out the back of the cabinet and drill a 2″ hole through the roof to add and connect another roof vent.
I believe that many 339DS’s from various production years have the same problem, but Forest River refuses to notify the customer base or implement a recall…
a case of summers eve in the camper should do the trick.
I get a gas build-up. Nearly everytime I flush gas bubbles backup. It happened some in the large black tank. It is nearly all the time now in my small black tank. I empty it almost daily when on the road plus rinse it out. Could the vent pipe through the roof be clogged?
We solved the sewage smell in our trailer when we replaced the worn out rubber seal between the toilet and the black water tank. You won’t be able to see this seal until you unbolt the toilet and lift it out. Even our trailer manufacturer did not know about the existence of the seal!
I quit using tank treatment in my tanks. Breaking down waste is not necessary, and can be detrimental to a clean tank. I don’t want “goo” when I am during the tanks, I want everything to come out the way it went in. The trick is to add plenty of water (black tank) before use, and every time you flush. Lots of water keeps stuff suspended and it floats right out when you dump. No sense having digested goo coating the sides and bottom of the tank! And your tank monitor probes don’t like goo sticking to them either.
For two years before I found the black tank vent pipe burried in an interior wall that was not routed to a roof vent we had sewer odor inside our Class A DP. Apparently Forest River “forgot” to connect the black tank vent pipe to a roof vent??
It was extremely difficult to locate the source of the odor but now the problem is fixed!
With RV’s always expect the unexpected!