I have to start this post about the composting toilet by saying that I can’t talk about what it is and how it works without talking about using it, if you know what I mean. So, if that level of detail isn’t your cup of tea, you may want to skip today’s post. Instead, you can read an oldie but a goody. How about the story of blowing a tire on the Alaska-Canada Highway on my way to begin RV Life? If you stick with me, I’ll share everything I’ve learned and figured out out the composting toilet. It’s going to take four weeks to get this job done.

Today, we’ll start with the basics about the composting toilet.

What Exactly Is a Composting Toilet?

A composting toilet is a self-contained toilet. One that doesn’t require water for flushing (you might hear them referred to as dry toilets) or access to a sewer for disposal.

Cartoon girl shrugging her shoulders.

Of course, since I live in an RV, I’m talking about it in terms of my RV. But RVs aren’t the only place composting toilets are used. They are popular on boats, in cabins and in tiny houses.  

If you have a few minutes, read the article on Wikipedia on the subject. In addition to learning there are actually three different types of composting toilets (which was new to me), you also learn the early history. I found the history interesting. After the Great Stink in the summer of 1858 in London (which I’d never heard of before and, yes, that’s really what it was called) caused by all the untreated sewage, a clergyman invented what he called the Dry Earth Toilet. It never took off because, by then, water-flush toilets connected to a sewer system were taking hold.

The Language of Bodily Functions

We use a lot of different words to describe what we do in the bathroom. There’s the clinical: urination and defecation. The colloquial: pee and poop, or #1 and #2. And then there is the vulgar which I won’t share here because I intentionally keep this blog G-rated. But if you are over seven years old, I’m sure you know what I mean.

But, for the purposes of this post, we are going to use the terms liquids and solids. Until I began researching composting toilets, these were two words I’d never heard to describe what we do in the bathroom. However, it is the most common language used when speaking about a composting toilet.

Not All Composting Toilets Are Alike

Although they function alike, different brands of composting toilets may be slightly different than what I describe here. I only have experience with Nature’s Head. I have seen some other brands websites that claim to be the most popular or most purchased brand of composting toilet. However, I take those self-proclaimed statements with a grain of salt. If you look at other bloggers and vloggers, it seems most have a Nature’s Head. That said, if you are looking to get one, it would be worth your time to do your research.

Further, I have no experience with black tanks as I opted for the composting toilet during my trailer build. When I comment about black tanks, I rely on what I’ve read, heard and talked with others about.

How a Composting Toilet Works

The key to understanding how a composting toilet works is to understand that you only get sewage when you mix liquids with solids. And sewage, I’m sure you know, is a health hazard. It’s why RVers who have a black tank (the tank that holds everything you flush down the toilet) must wear gloves whenever they are dealing with the black tank. In other words, they wear gloves while connecting the sewer hose to a sewer drain, when unhooking the hose or when they are at a dump station. They wear gloves because there is the chance of direct contact with sewage.

So, once you understand sewage, the real key to understanding how a composting toilet works is super simple. You understand that a composting toilet does not create sewage. By keeping liquids and solids separate, as you do in a composting toilet, you don’t have any health hazard worries.

Keeping them separate also means you deal with them separately. But before I talk about dealing with the contents of the separate liquid and solids containers, let’s understand the components of the toilet.

Parts of a Composting Toilet

There are three main components of the composting toilet. Each one is a separate piece and all three fit together. There is the main base which is where the compost and your solids go. The tank that collects your liquids tucks into the front of the base. Then there is the top which slides onto the base and is bowl and lid of the toilet.

In addition to the three main components, there are three smaller (but still important) components of the toilet. I’ll talk about them in more detail below, but those components are an agitator, a fan to pull air into the base and a vent tube for that air to escape.

Side view of the Nature's Head composting toilet. Color is white granite.
Borrowed from the Nature’s Head website. This is a great side view of the composting toilet. You can see the three main parts–base (the back bucket/bin is where the compost goes), the liquids tank and the top which is the bowl of the toilet.

Using the Composting Toilet

If you open the lid and look into the bowl, you’ll see two things. First, there are two holes at the front of the bowl that lead to the liquids tank. Second, you’ll see a four-inch squarish flat disc at the bottom of the bowl, just behind the two holes for the liquids. That is the flap or trap door that opens with a lever on the side of the toilet to gain access to the solids bin.

Again, what you are seeing as you look into the bowl is what we’ve been talking about all along, the separation of liquids and solids.

Using the Liquids Tank

Here are a few helpful hints when using the tank. As much as possible, you want to direct your liquids to the liquid tank. This means, you’ll want to sit a bit forward since the liquids are directed toward the front of the bowl. And, men, you need to sit. This is a recommendation on the toilet’s website. Plus, just logistically, it makes the most sense.

One of the things that happens when too much liquid makes its way into the solids bin: sewage. It’s messy and disgusting from what I understand.

Keep a spray bottle on-hand filled with half water and half vinegar. Or at least that’s what is recommended. I find it simpler to just have the bottle filled with all vinegar. After using the toilet for liquids, do two or three pumps from the spray bottle of vinegar to help the lingering liquid drain into the liquids tank.

Using the Solids Tank

So, since you scoot a little forward to use the liquid tank, you’ll want to scoot back to use the solids tank. If you are too far forward, you risk solids dropping into the two liquid holes and into the liquid tank. It’s not tragic, but it wouldn’t be very fun to clean.

To use the solids bin, open the trap door. Solids drop straight down into the compost. You have two choices when it comes to compost: organic coconut coir or organic sphagnum peat moss. Whichever way you go, organic is recommended by the manufacturer. Next week, I’ll go into more detail about why I use coconut coir.

After you add solids to the compost bin of the toilet, it requires two things to break it down the solid. Compost and oxygen. The website explained it this way:

Composting requires aerobic bacteria to work. An aerobic organism survives and grows in an oxygenated environment. Oxygen is the key ingredient that allows aerobic bacteria to break down waste quickly and without odor. Mixing in either the sphagnum peat or coir breaks apart the feces to allow the aerobic bacteria to get it’s oxygen.

So, after using, twirl the agitator two or three full turns to get the process started. The fan runs air through the bin.

The fan, in case you are worried, uses a negligible amount of battery power (1.7 amps in 24 hours). It’s a good idea to keep an extra fuse on hand. I’m not sure if those are available on Amazon or not. I ordered mine directly from the manufacturer.

One More Thing About Oxygen

I saw a YouTuber who bought a Nature’s Head to install in her conversion van after a year of dealing with a black tank. She did a ton of research and, it turns out, you can make the system work without running a fan. In her case, she didn’t want to have a hole cut into the side of her van in order to vent the air.

Instead, once a day, she would leave both the lid and the trap door open. The amount of air that naturally circulated was enough to meet the needs of the compost. I found it interesting to consider. It appealed to me especially after the bug infestation. Guess where they get into the toilet from? Yep, outside. They came down the vent tubing. But more on that grossness later.

How Often Are the Tanks Emptied

Of course, all I can do is make a big generalization when answering this because so many factors go into the answer. How many people are using the composting toilet? Do you drink a lot of water and other liquids? How much water is in your food? High consumers of fruits, vegetables and fiber will use the solids tank more frequently and will result in solids with a higher water content which affects the rate the compost can keep up with the need. And of course, in general how often is the toilet being used?

But I can offer a vague guideline based the manufacturer’s website for a full-time couple. And, I’d back it up with my own experience.

The liquids tank needs emptied every two to four days while the compost needs emptied and replaced every month or so (every 60 to 80 uses).

That said, the answer for you is super simple. You empty the tanks when it’s needed.

More to Come

So, this post is just the basics of what a composting toilet is and how it works. There remains so much more to share.

Next week I tackle prepping the toilet for use and emptying the tanks. I will answer the all-important questions about smell, toilet paper and can you use the composting toilet on days you aren’t feeling so hot (aka, vomiting and diarrhea) in the week after. And in the final post, we’ll talk bugs.

If you hung in there all the way to the end of this post, did you learn anything new? Would you ever try a composting toilet? (Or maybe you have to read about bugs before you decide?)

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