Why Does My Camper Smell Like Pee and Sewer: How To Fix

Help! Why does my camper smell like pee and sewer? There’s nothing like going out to run an errand, returning to your camper, and as soon as you open the door you’re hit by the stench of an interstate rest stop bathroom on a hot day in August. Welcome home?

Typically, campers smell like pee and sewer because of faulty toilets, dirty holding tanks, broken vents, and improper practices related to camper toilets and waste tanks. Fixing the problem involves a basic understanding of the waste system, preventative measures, and restorative courses of action.

So, let’s start with a cursory understanding of the waste system, examine each part, and prescribe preventative and restorative measures so your camper will smell fresh and clean…or at least not like an outhouse.

The Waste System

Camper Waste System

The camper waste system functions primarily by gravity and airflow. Waste funnels into a tank to be stored until the tank valve is manually opened. With the valve open, the waste, assisted by air, begins to flow out of the tank and into the underground septic tank.

There are two tanks: a grey one and a black one. We will discuss these in more detail later. Needless to say, the process is essentially the same regarding the collection and storage of waste and emptying it with the aid of a vent (air).

When the valve is opened, waste flow is aided by a vent that runs through the wall (or closet) from the top of the tank to the roof. The vent allows air to enter the system and increases the steady flow of the liquid. It functions similarly to punching a hole in the bottom of a gallon jug when pouring out water. When positioned upside down without the hole in the bottom, the water will gurgle out forcefully and inconsistently. The hole allows air to enter the jug and helps the water pour smoothly.

Now that we have a very rudimentary understanding of the waste system, let’s move to one of the three major culprits of a camper smelling like pee – the toilet.

The Toilet

We have to start with the toilet because that is where the pee is deposited – we hope. You might want to check around the toilet first. It’s not uncommon for a guy to miss on occasion, so we might as well rule out “bad aim” first.

Ok, now that we’ve ruled out bad aim, let’s inspect the toilet.

Some camper toilets have a history of seal issues. One such toilet is the Dometic 300. You can find the manufacturer and model by inspecting the base of the toilet. It might be on a sticker on the back of the toilet base. Use a mirror or take a picture with your phone to see the sticker better.

The Dometic 300 had issues with a seal inside the toilet, which caused liquid to seep into an inaccessible area within the toilet body. This allowed the pooling of toilet liquids, which were not visible. Imagine a little reservoir of urine and feces fermenting in the back of your toilet, and you don’t know it is there. You can’t see it, but you definitely smell it. Because you do not address the odor’s source, no amount of cleaning the toilet or surrounding area will remove the smell.

One of the solutions in Youtube videos was to take the toilet out, take it apart, and repair the seal. No fricking way was I doing that gross job, so I turned to a Facebook group. There, I saw people ordering replacements for the Dometic 300 series directly from the manufacturer.

So, I decided to call Dometic. I don’t think there was an actual recall, but they were very helpful. Be prepared when calling Dometic, as they require certain camper information to verify your camper has a Dometic toilet. After verification, they gave me a choice to either get the same model delivered to my camper free of charge (no thanks), or I could upgrade to the 310 series with the porcelain bowl and soft close toilet seat for an additional $75. Only $75 to avoid odors, not hear the plastic creaking every time someone repositions on the toilet, plus a soft close seat? DONE! Mama didn’t raise no fool ; )

Dometic 310 Toilet
Dometic 310 Toilet
Click the image to see the reviews

Another culprit of foul smells from the toilet is the black rubber seal at the bottom of the bowl. This seal can become dirty and allow water to leak out of the toilet bowl and into the blacktank. If the black rubber seal doesn’t hold water, then gases from the black tank can seep into the bathroom and cause your camper to start stinking like a sewer.

Camper Toilet Cleaning

You need to clean the seal, especially the underside, so it seals tightly with the flapper valve (the white trap door at the bottom of the bowl). There are different ways to do this, but I will only share the two I used. Both involve the Dollar Store ($1.25 Store now) and require you to turn off the water supply to the camper before beginning.

1) Buy a camper manufacturer-approved thick liquid or spray cleanser, gloves, and an inexpensive disposable bottle brush. Run a string through the eyelet of the brush wand and wrap it around your wrist so you don’t lose the brush in the black tank. Have a trash bag for the used brush near the toilet before you begin. Now put the gloves on.

With the water off, depress the foot pedal to open the valve at the bottom of the toilet. Apply the thick clinging cleanser to the top of the valve, under it, on surrounding walls, and in the neck of the tube leading from the toilet to the black tank. Close the valve, spray the top of the valve again. Let the cleanser sit for a few minutes before you begin. This will loosen debris (you know what I mean).

Secure the brush string around your wrist before you begin so you do not drop the brush as you clean. Gently push the brush through the toilet opening towards the black tank and scrub the cleanser-presoaked areas, particularly the underside of the rubber seal and other nearby areas. Slowly and carefully remove the brush past the toilet valve after cleaning to avoid a potential mess.

Tip: My wife trimmed the bristles of the brush so it would fit through the opening without touching the sides. If you don’t do this, the bristles may flick water and debris in your direction when you pull it out – much like when you run your thumb across your toothbrush. But, it’s not toothpaste that’s flicking back in your face. Yuk!

Camper Toilet Splatter

2) Buy a camper manufacturer-approved thick liquid cleanser with an inexpensive disposable sponge brush and wand attachment. Use the same string through the eyelet method to secure it. The instructions are the same as outlined above, but the tool is different. The sponge is not as strong as the brush, so you need to apply a little more pressure, but you don’t have to worry about the possibility of toilet face splatter.

As you are cleaning the seal, if you can safely go a bit further, clean the hinge just below the trap door of the toilet. This is connected to the foot pedal and has a tendency to collect waste that passes by it before it enters the black tank.

Make sure you have a plastic disposal bag ready to put the used brush or sponge and gloves in right after you clean the seal so you are not tracking it in your camper. Immediately take this bag out of your camper and throw it away at the campsite’s dumpster.

Now you can turn the water back on and enjoy a sparkling clean, odor-free toilet!

Toilet Smell Summary:

  • check for bad aim
  • consider a replacement if you have a flawed toilet
  • clean the dirty seal and hinge

The last item regarding this toilet section is preventative. Keep a small amount of water in your bowl even when you are not using it. The water serves a few purposes. It makes sure the rubber seal does not dry out and become brittle; it alerts you if the seal is malfunctioning because the water will leak out if the seal is compromised; it functions as a barrier to keep the black tank smells beneath it from entering your camper.

Speaking of tanks, let’s discuss them to understand how to remedy and prevent problems.

The Tanks

There are generally two waste tanks in a camper: the black tank and the grey tank. The black tank is for the toilet; the grey tank is for sinks and showers.

The Black Tank
Let’s take a look at the obvious odor culprit: the black tank. The black tank’s purpose just seems gross; it is a large container that holds pee and poop for days – just beneath your camper floor. Of course at some point, there will be bad smells, but there are a few things to minimize unpleasant sewer smells you may encounter.

A phrase I want you to burn in your mind and repeat three times out loud is “WATER IS MY FRIEND”. Come on, repeat after me: Water is my friend, water is my friend, water is my friend. Ok, now with that understanding, let’s begin.

Water is my friend

Imagine if you pooped, and there was no water in the black tank. With each bowel movement, a mound would start to build, rising toward the base of the toilet. When it’s time to empty the black tank, how would you get that solid mound out? The solids would never make it out of the tank unless they were liquified. This is why water is your friend. It liquefies poop so it will flow more easily out of the waste valve and through the hose connected to the septic tank.

Before you use the toilet or right after you drain the black tank, make sure you fill the toilet with water 2-3 times and flush it to provide a base to liquefy the solids.

It’s not just water that will help liquefy the poop. You also need something to help break it down. We tried a few different suggestions and settled on a product HERE. Mix it in a small jar, pour it into the toilet bowl, fill the bowl, and flush it into the black tank. We were Happy Campers with how it helps to prevent black tank smells for 5-6 days. We emptied our black tank every 7 days, even if there was no odor.

Another product that comes highly recommended is this ONE. It was convenient because there was no mixing, and it was prepackaged. Just open it, pour it into the toilet, add water, and flush.

We’ve also used the throw-in packets, but we didn’t care for the chemical smell they emit. See for yourself, and check them out too HERE.

We also heard of and tried the geo method, which is a mixture of Calgon and Dawn dish soap. A lot of people swear by it, and I’m a sucker to try something new. We gave it a shot. We didn’t see (or smell) the great results reported by others, but I encourage you to do a Youtube search and try it firsthand.

Now that we’ve prepped the black tank with enough water and an additive, we have to discuss dumping and cleaning the black tank.

I suggest dumping the black tank when it starts to get close to full. How do you know? Believe me, you’ll know. How? Two ways.

  1. By experience; you’ll hear the water make a different sound when flushed as the tank becomes closer to full. To help, get a flashlight, shine it in the bottom of the toilet, and depress the foot pedal fully to open the valve. You will be able to see the water in the black tank and its distance from the toilet (how close to full it is).
  2. By tank sensor, if it works. Many people have black tank sensors to gauge how full their tank is, but it is not uncommon for them to malfunction. Our sensor stopped working soon after we bought our new camper; the service manager said they are notorious for not being accurate. Debris and toilet paper can stick to the sides of the tank interfering with sensors. Rely on them at your own risk.

Our camper had a black tank flush system, which was a place to hook up a hose and wash out the black tank with water after it had been emptied. We would close the release valve, add dish soap and disinfectant to the black tank through the toilet, fill the black tank again with clean water using the black tank flush, and let that water and cleansing combination sit for 30 minutes.

I do not recommend doing this alone because two communicating people are needed to avoid tank overflow through the toilet and onto your floor. After the 30-minute cleaning, open the valve and empty the tank. Then prep your toilet as described above with water and an additive prior to use.

You would be surprised to see the waste and debris that comes out after the first black tank flush fill. Sometimes, we would even do a second black tank flush and be amazed at the water, which looked noticeably cleaner. Flushing the black tank and removing debris also aids in odor reduction.

Black Tank Smell Summary:

  • “Water is my friend”
  • Use a tank additive
  • Dump Black tank when close to full
  • Flush or fill and drain again for better cleaning

The black tank has a much-ignored brother: the grey tank.

Camper Tank Brothers
The Tank Brothers

The Grey Tank
The grey tank doesn’t get blamed for smelly campers nearly as much as the black tank, but can also produce some stinky problems. Food particles go down the kitchen drain and into the grey tank. Toothpaste, soap residue, shaving cream, and shaved hairs enter the bathroom sink drain and into the grey tank. Shampoo, body oils, and washing machine water drain in the shower, then into the grey tank. Now imagine all those items mixing together and sitting in a tank under your camper in the summer heat. Do you see where I’m going with this? The grey tank also has the ability to produce awful camper smells.

Grey Tank Drains
Grey Tank Debris

We didn’t have much of a problem with our grey tank, and I think it was because of the way we used it. In general, we left the grey tank valve open. We would sometimes close it a day or two prior to dumping the black tank to flush the waste line that goes into the campground septic tank. In general, we kept it open because it fills up quickly, and it’s irritating when the shower starts to fill with grey tank water when you are trying to get clean.

If you are having smelly problems with your grey tank, try closing the valve, adding a disinfectant, and adding liquid soap to cut the oils and grease from food and your body. As the grey tank fills, the water will mix with and remove smelly debris from the tank walls, which will be removed upon emptying the tank.

Grey Tank Smell Summary:

  • In general, you can function with it open
  • Sometimes close 1-2 days before dumping the black tank
  • Close the valve and add disinfectant to clean

One last item I would like to pass on regarding the tanks. If you are going to be traveling, some campers suggest adding some Calgon, Dawn dish soap, and two bags of ice. The idea is these will mix together and the ice will slosh around and clean the sides of your tanks while traveling. We never traveled with our camper, but many campers swear by it.

Now let’s bring some air into the conversation in the form of vents.

The Vents

Some campers have air admittance valves under the sink that let air into the system to help the water move better. These valves are designed to be one-way valves that only let air into the system, not let the air out of the system and into your camper. Imagine the smell of your camper if your grey tank is stinky and grey tank air is coming back into your camper. The valves prevent this problem.

If these valves become faulty, you’ll need to replace them. They should easily unscrew, and then you screw in a new one. The recommended vents to replace the cheap vents that come with the camper are located HERE. Always check fittings for compatibility first.

Other vents that can become faulty or may not perform as well are the vents that connect to the waste-holding tanks. It is imperative these work properly. Remember the water jug explanation? Imagine if your black tank wasn’t getting air and the waste was gurgling and splashing up towards the toilet when you opened the release valve. Hot cocoa bubbling trouble – no thanks! Thankfully, I never had problems with these vents, but they can be an issue for some campers.

There are two waste-holding tank vents/vent covers that are highly recommended.

The first vent/vent cover claims to prevent odors and gasses from invading the living space, speeds up waste breakdown, eliminates the need for chemicals, installs easily, universally fits, works in any wind condition, is available in black or white, and has a built-in bug screen. It sounds promising and can be found HERE

Camper Vent
Click the image for details

The second vent/vent cover claims to use the power of the wind to draw holding tank odors out of the RV, rotates 360 degrees to follow the wind, attaches easily to most RV plumbing vents, and requires no drilling into your rooftop. It can be found HERE

The last vent doesn’t deal directly with the waste system, but it can surely help to dissipate stinky and stale smells. This is the bathroom roof vent. Our vent had 3 different speeds and did a pretty good job of pulling stale air out of the camper. Make sure you have another window or two partially open so you are creating a sort of cross breeze.

You can also have the roof vent lid open without the fan motor running to air out the camper. Again, make sure you have some windows open too. If you decide to try this, make sure you have a vent lid cover with a bug screen so an errant bee doesn’t get in and ruin your day. The brand of cover we used is HERE. It had EZ clip hardware and no need for drilling. Make sure you check compatibility with your camper before purchasing as there are different styles.

Vent Smell Summary:

  • Check and fix air admittance valves
  • Upgrade or replace roof vent covers
  • Use bathroom vent to air out the camper

It’s very important to prevent your camper from smelling like pee and sewer and learn methods to fix it. We have discussed the waste system, so you have a cursory understanding of how it works. We also analyzed the main culprits causing bad smells in your camper. In addition, maintenance, remedies, and preventative measures were prescribed. These tips should keep your camper smelling pleasant… and nothing like a south Georgia truck stop restroom on I-75 in July.