Learning the basics of what a compost toilet is and how it works is only the beginning when deciding if you want to use one in your RV instead of the more traditional black tank. You have to go into the purchasing feeling confident that you can do what’s necessary to maintain it. By describing the steps of preparing and emptying the toilet (both the liquids and the solids tanks), I might be able to help you in that decision.

Next week I’ll talk about the general maintenance as well as answer the questions people want answers to but are often embarrassed to ask. And after that, we’ll move on to bugs, an issue, unfortunately, I can speak about from experience.

Coconut Coir as Compost

Once installed, the only thing to do to prepare the compost toilet for use is to prepare the compost. As I said last week, you can use either coconut coir or sphagnum peat moss (organic is recommended). Most people I know use the coconut coir. I suspect the reason has to do with space. The peat moss comes loose and in big bags. Whereas, you purchase the coconut coir in dehydrated bricks.

As a side note, I did have a friend who tried the sphagnum peat moss once and said it had a much stronger dirt smell than the coconut coir. On top of that, it created a lot of dust. She would never use it again. If you decide to try the peat moss, be sure not to get Miracle Grow brand or any brand that enhances the peat moss.

Coconut coir, as the name implies, comes from coconuts. It’s the natural fiber from the husks of the coconut. The bricks are heavy and dense, but relatively small, The brand I get has the dimensions of 12” x 12” x 4.5” and weighs 11 pounds. However, when water is added to the full brick it expands to 15 gallons. So, a single brick lasts quite a long time.

Since the coconut coir is my only experience, I describe preparing the compost with the coconut coir. The peat moss, I think, is ready straight from the bag.

Preparing the Compost Toilet for Use

Bring the base of the compost toilet out onto the floor of your rig (if room) or a table either outside or inside your rig. Another option is to prepare the coconut coir in a bucket or gallon-sized bag.

To prepare the compost, cut a chunk of the coconut coir from the brick and put it in your base. The brick is so dense, it takes a knife and some serious pounding to get the pieces to break off. Be careful. We don’t want anyone having to tell a story of losing a finger from a toilet. That would just be embarrassing.

Note: The coconut coir expands a lot so if you put a chunk in that fills the bottom of the base, you’ll end up with way too much final product. But no worries if you make too much (in fact, below I’ll tell why you might actually want to), just keep the extra in a sealed Ziplock bag for a future use.

Package of Coco Coir brand of coconut coir, bleach tablets, scrub brushes and two pairs of
Supplies for preparing and emptying the compost toilet. Coconut coir, rubber gloves, bleach tablets, bucket, brushes and a kitchen spoon.

Next, pour a couple cups of water over the chunk. Now, here you have two options. You can give the water about 30 minutes to absorb into the coconut coir before you put your hands in and break up the pieces, test the wetness level and go from there. Or, you can dig right in and help the coconut coir absorb the water by breaking it up and working it through your fingers. Add additional water and coconut coir as needed.

I do the latter. Once I start the project, I just like to keep going until its done. Plus, there is something meditative about the act of working the coconut coir into a nice soil-like consistency.

You will want to use gloves for the project otherwise you risk getting fine slivers that sting and can be hard to remove. I always use the thicker dishwashing gloves made of rubber rather than the thinner first-aid gloves made of latex, vinyl or nitrile to ensure nothing pokes through.  

Create enough compost so that it comes up just under the agitator when you have the agitator horizontal, as seen in the feature photo.

How Do You Know the Compost is Prefect?

On this question, experience helps. That rich black soil you buy in bags to pot a houseplant is a good gauge in looks, smell and texture. But, that said, I have learned you want the compost on the drier side rather than the moister side. Human waste naturally has moisture in it and by starting out on the drier side, you leave room for the compost to absorb some of that moisture. It can be an ineffective mess if the compost gets too wet.

The other tip I can offer is to make a little bit extra compost and put it in a Ziplock. For a couple days leave the Ziplock opened until it gets quite dry. Then, when starting out, instead of bringing the compost to just below the agitator, go an inch below the agitator. As you use the compost toilet, if you find the compost, once mixed with solids, is getting too moist, toss in a couple handfuls of the dry compost to help keep it at a perfect level of moistness.

If you eat a lot of food with a higher water content (think fruits and vegetables), it will be to your advantage to start with a drier compost. And, even then, you might find you need to add more handfuls of the dry stuff from the Ziplock.

How Long Will a Batch of Compost Last?

If I’m using the composting toilet regularly (and, really, I don’t because I use the restrooms and bathhouses at RV campgrounds), then I change out my compost once a month or so. I admit, it’s probably more often than is truly needed. But monthly is easy to keep track of and I never risk letting it go too far beyond what it can handle.

In addition to the 60-80 uses guideline from the manufacturer, another telltale sign that it’s time to change the compost is that the agitator becomes quite hard to turn. In other words, the compost is thick with material, not light and fluffy like when you first make it.

One note here. Although the compost toilet breaks down the solids, that process takes six to eight hours. Therefore, it is recommended that, first, you wait at least eight hours from the last use before emptying the compost bin. Second, because there is a possibility that fecal bacteria may still be present, it’s recommended you wear gloves during the process of emptying the composting tank and preparing a new batch of compost. It’s fine to wear the same pair of gloves to both empty the old compost and to prepare the new compost.

Emptying the Compost Toilet

Okay, so emptying the used compost. First remove the base from the bathroom. That’s easy, it’s just a thumb screw on either side of the base. When you lift it out, you’ll be taking the entire toilet—all four components as described last week.

There are a couple of protruding parts on the base of the compost toilet. One time when I was emptying it, I scratched my dining table. So be careful you don’t repeat my mistake.

First, remove the bowl/lid part which you do by unlocking the sides, lifting the bowl all the way up and then sliding it off the hinge. Set it aside. Also, remove the liquids tank from the base and set it aside.

The base is awkward because it’s so big with the holding area for the liquids tank so make sure you have plenty of room because you will be flipping it over. But, first, stretch a kitchen garbage bag over the base. A regular 13-gallon kitchen bag is a tight but perfect fit. Though stretch it carefully so as not to rip it.

Then flip over the toilet base, bang on the sides a few times and, if you can somehow find a third hand, spin the agitator. Bang on the sides a few more times. Then put the toilet upright, take off the bag and check your progress.

White trash bag put over the top of the bin of a compost toilet.
Borrowed from Nature’s Head website.

Now, let’s get honest here. I’ve seen YouTubers turn it over once and declare it “that easy and you’re done.” The manufacturer’s website says that too. But that’s not entirely true. Not quiet that simple and easy and fast. Over time, the compost gets packed into the corners, clings to the walls and to the agitator. Interestingly, the compost in the corners is almost always completely unused because it’s out of the range of the agitator.

I use a white plastic kitchen cooking spoon (I brought way too many into RV life) now dedicated to digging around in the composting toilet. I use it to loosen the compost from the walls and floor, the corners and from the agitator. Of course, you can also use your gloved hands. So, once you have loose compost, reattach the kitchen bag (or get a new one) and turn everything upside down again. Repeat as needed.

Making New Compost

The goal is to get most of the compost out of the bin. It’s actually discouraged to clean the bin entirely. By leaving a few bits of matter clinging to the walls and the agitator, you actually help the next batch start its work.

So, once the bin is mostly empty, break off a hunk of the dried coconut coir brick, add water and proceed to make a fresh batch of compost. Or, of course, add the sphagnum peat moss if you are going that route. To further help the compost start its process, take your fresh compost and rub it over the walls and agitator. It both “cleans” those areas and, as I said, gets the composting process started.

Since You Have the Thing Apart

Okay, the liquids tank is a much simpler process. It gets full, you remove it from the base and empty it.

But, let me offer a cleaning tip. You can get a bit of build up in the liquids tank so, on occasion, it’s a good idea to clean the liquids tank. It actually isn’t super easy to do because of the small opening at the top. It’s not like you can take a sponge and wash it down. I tried a skinny brush with a long handle but the angle is too awkward to be able to really scrub it.

What worked for me is bleach. Now, here is a big science-y word of caution that, yes, I learned the hard way since I didn’t do very well in science classes.

The chemical components of urine and bleach react to each other to cause smoke. Scared the crap out of me the first time it happened. It looked like I was creating a witch’s brew, the way smoke curled out of the tank’s opening. Not sure if the chemical reaction is enough to create an explosion, but let’s not find out. Obviously, that first time, I did not blow up. That time, I reacted like a kid by figuring if I couldn’t see it, it wasn’t happening. So I put the lid on the tank and set the tank outside.

I know. I know. Don’t hate me because I’m a science dud.

Now, before I begin the same cleaning process, I rinse the tank several times well with water. Then I fill the tank about halfway with water, add either a couple bleach tablets or a bit of liquid bleach. Let it set. If you do this before you start emptying the compost and making new, by the time that project is done, you’ll have a nice clean liquids tank. Swirl the brush around your liquids tank, then dump and rinse well to make sure all the bleach is out before you use it again.

Since I’m sure many of you will not feel comfortable with my smokin’ process (understandably so), let me also offer two other options as recommended by the manufacturer.

You can empty the tank, fill it was water and one-quarter cup of Lemi Shine Detergent Boost. Wait 24 hours. Rinse clean. The other option is to empty and rinse the tank. Then add about an inch of white vinegar and some gravel. Put on the lid and give it a good shake. The gravel acts as a scrub brush. Dump the gravel and you are good to go.

Next week, I’ll share how and where you dispose of liquids and used compost.

Bowl and Lid Cleaning

The top part, if you wipe out occasionally as you use it and do the squirts of vinegar after each use as suggested last week, it won’t need too much cleaning. But, again, since you have the whole thing out and apart for the compost change, it seems the perfect time to give this a good cleaning too.

I find it easiest to do this cleaning job outside with your water hose but I also have a small rig. Depending on your rig, you could do this in your kitchen sink or shower pan.

Close the lid and turn the bowl upside down (so it’s resting on the closed lid). Then, simply hose the thing down. I also take the skinny flexible brush I used in the liquids tank and brush inside all the small crevasses where the water pressure might not reach. Do this with both the trap door for the solids open and closed.

Turn it right side up, open the lid and do it all again.


Reassemble everything. And don’t worry about it again until next time you’re ready to change the compost.

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