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How Does a Composting RV Toilet Work?

How Does a Composting RV Toilet Work?

One of the great comforts of an RV is having your own private bathroom with you wherever you go. Surprisingly, there are multiple choices for RV toilets as shown in our post “RV Toilet Talk” from a few years ago. You may have heard of an RV composting toilet, a once unique option that’s become more common in the past several years. If you’ve ever found yourself wondering, “How does a composting RV toilet work?” you’ve come to the right place.

This short post is an overview of what a composting toilet is and how it works, helping you to decide if it’s the right choice for your RV. The post is short because composting toilets are actually rather simple devices!

What Is a Composting RV Toilet?

Rather than using water to flush waste to a holding tank from where it’s later dumped, a composting toilet combines composting material with the waste which, together, later becomes compost. This represents an organic approach to handling waste, with an end-product that can eventually become fertilizer.

A composting toilet uses no water at all and so it requires no plumbing.

Photo of a woman dumping her RV's black tank at a dump station

With an RV composting toilet, the infamous task of using an RV sewer hose to empty the contents of the black water tank may be a thing of the past, but you’ll still have to dump your gray tank!

It’s not too dissimilar from a portable camping toilet, but there ARE some distinct differences. Let’s take a look at how it works.

How Does a Composting RV Toilet Work?

A composting RV toilet separates liquids from solids. Liquids are deposited into a container typically located at the front of the toilet, and solids are deposited into the back area of the bowl, where they’re released to/deposited into a holding container below via a small trap door.

That solid waste holding “tank” contains organic material such as peat moss or coco coir. Once solid waste is deposited into the tank, the user turns a crank located at the side of the toilet to combine the organic material with the solid waste.

While not all composting toilets are the same, most share three functions in common:

  • They separate liquids from solids.
  • Solids mixed with the composting materials are virtually odor-free as they compost.
  • The composting material + waste is safe to handle during disposal.

Liquids are emptied with frequency, and the composting solids are emptied on a schedule that is based on how much the toilet is used. Obviously, if several people are using the toilet, the composting material would need to be changed more frequently.

Using two people as an example, the liquid container might need to be emptied once every day or two, while the tank containing the solids + composting material might need to be emptied anywhere from every two weeks to once a month.

Are There Different Types of Composting Toilets?

There are different types of composting toilets, though one is more likely to be used in an RV.

The most common types of composting toilets are single chamber and multi-chamber models that are either self-contained or central composting systems.

Single & Multi-Chamber Composting Toilets

A single chamber composting toilet uses an aerator to evaporate liquids out of the combined waste in the chamber, though sometimes the humus must be removed from the toilet tank to thoroughly dry.

More popular is the multi-chamber toilet which separates liquid waste from solid. This is the most common type of RV composting toilet.

Both types of composting toilets will typically have small ventilation fans to remove odors from the composting chamber and to facilitate composting & moisture removal.

Self-Contained and Central Compost Systems

A self-contained composting toilet is an all-in-one unit, with both the toilet and composting tank in one area. This is the type of system you would find/install in an RV.

A central compost system looks like a traditional toilet but has a storage chamber either just below the bathroom or in a basement. This is more commonly used in a more traditional home that is in a fixed spot on land. They have more space available and can hold compost for a far longer period.

Nature's Head Self Contained Composting Toilet with Close Quarters Spider Handle Design
  • No one - and I mean no one - will beat my customer service and individual support
  • Easy to install by any reasonably handy person.

Watch This Video To See What an RV Composting Toilet Installation is Like:

If a picture’s worth a thousand words, a video is worth at least 10,000! Here our friends and co-hosts on The RVers Tom & Cait Morton show the installation of their composting toilet. Not every installation will be the same, but Tom & Cait cover a lot of the details typically involved.

Is a Composting RV Toilet Right For You?

Now that you understand how a composting RV toilet works, and even a bit about what’s involved in installing one, would you consider using one in your RV? Give us your #1 and/or #2 reasons for/against having one in the comments down below.

By the way… we spent a week with our friends Nikki & Jason Wynn in Panama a few years ago, helping them sail their catamaran through the Panama Canal. The head (bathroom) in our cabin was equipped with our own private composting toilet (two of the three toilets on their boat are composting). We had absolutely zero issues with odor from it.

That’s also the composting toilet from Nikki & Jason’s old motorhome pictured at the top of this article, and I smelled nothing while filming it for the video below.

So in case you’re wondering, if not for the fact that our toilet is mounted on a pedestal about 6″ above floor level (which would require substantial structural modification to change), we’d have installed a composting toilet in our rig years ago. With all the power we have available on our roof, water is our limiting factor on boondocking trips. And composting toilets save a TON of it! Plus, you don’t even need to worry about selecting RV safe toilet paper.

But maybe you’re more of the outdoors type and are looking for an option for less pampered camping, where you don’t have a toilet at all? Then maybe the Krapp Strapp is the thing for you?

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Judy Bowen

Tuesday 29th of March 2022

I have IBS which mean a fair bit of liquid stool. Would this be a problem for a composting toilet in that it is less solid?

Meg Magruder

Tuesday 28th of March 2023

@Judy Bowen, I have a Natures Head. We have used when camping and Tailgating for several years. It would likely need some experimenting on what would be the most useful fill material. Maybe a mix of fill possibly some clumping litter. Or a more powerful fan to help "dry" the solids area.

Think of it as a human litterbox.


Wednesday 30th of March 2022

Sorry to hear, Judy. Composting toilets should handle anything that comes out. It just might need to be emptied a bit more often, or require a bit more composting material.

Gay Tacoma Washington

Tuesday 29th of March 2022

Interesting. I've heard of the Composting Toilet. It seems like a better idea than flush toilets, since it doesn't use water. But I've never used a composting toilet. I don't know how it works.

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