What is a composting toilet? Your complete guide to how they work

What is a composting toilet? Your complete guide to how they work

Everything environmentally friendly matters more than ever before, and that’s why we should all be asking, “What is a composting toilet?” Composting toilets are where it's at, and you won't believe how much these toilets can help save the planet – and save your sanity when it comes to tiny spaces, living off-grid or on the road!

So here's the lowdown on these eco-friendly toilets and why compost toilets are the perfect solution for camping, campervan bathrooms, van life, tiny homes, and living off-grid.


TL;DR summary

If you are looking for a portable composting toilet to take with you on the road, then a urine diverting dry toilet (UDDT), like Cuddy, is your best bet. It works by diverting the liquid waste for ease of emptying, allowing the solids bin to start the composting process - which drys out and reduces the volume of your poop. Separating the liquids and solids stops the formation of sewage. This is really the first bit of magic. As a result, you get more time on the road with a toilet system that saves water while giving you an odor-free experience. All you need to maintain it is a sprinkle of sustainable peat moss or carbon-rich material.


What is a compost toilet?

Before we begin, we should address the question, “What is a compost toilet?” A compost toilet is usually a waterless toilet that uses the power of nature – decomposition – to turn human waste into nutrient-rich compost called ‘humus.’

Compost toilets create ideal conditions for microorganisms (microbes, bacteria, and fungi) to thrive by providing food, oxygen, controlled moisture, and the right acidity. To kickstart the process, a small amount of carbon-rich material like coco coir or sawdust is added to most composting toilets.

There are two types toilet manufacturers produce:

  • A self-contained system - mostly used in static settings, where liquids and solids are composted together over a longer period
  • Or split systems, like our Cuddy - much better for portable situations, where you have limited space to house a unit and humanure.

Wonderful waterless toilet

The most common waterless toilets are compost toilets, or dry toilets since they require no water to flush, come in different toilet designs, sizes, systems, and tank capacities, so they're perfect for everyone anywhere. Tiny homes, cabins, campervans, conversion vans, boats, back-of-trucks, off-grid living – no matter the size (or location) of your space, composting toilets have got you covered!

It is important to mention that not all waterless toilets are composting, so it is important to understand what system you are buying into.


But do they smell?

This isn’t a gross outhouse or a porta-potty that is the bane of outdoor adventurers everywhere; composting toilets are clean and smell significantly less than a typical toilet, all the while performing serious recycling mojo magic without using a drop of water – or, in the case of other toilet systems, gallons of water!



How do they work?

Compost toilet systems are self-contained, meaning they take care of the whole compost deal inside the toilet. However, the best portable bathroom option is a composting toilet with a urine diverter so that liquids are kept separate from solids. This removes the unpleasant odors that come from your waste so that even in the smallest of spaces, your composting toilet does not smell – although, for the exceptionally curious out there, if you put your nose near the composting bin, it will have the subtle scent of a mossy forest floor.

The best compost toilets separate liquids from solids; the liquids go into one chamber, whereas the solids go into a separate bin full of carbon-rich material such as sawdust, sustainable peat moss, or coco coir. These natural substances help break down the solid waste into dry compost material with the aid of oxygen, aeration, temperature, and aerobic organisms – Mother Nature knows best!


What are the advantages of a dry composting toilet?

Are compost toilets worth the hype? Let’s explore the pros and cons of toilets that compost.

    • They save money - Compost toilets save money because you dump them less often, no chemicals or special cartridges to buy
    • It also saves water and eliminates wastewater - They can save approximately 6600 gallons (24,984 L) of water per person per year
    • Reduces your reliance on old-school plumbing
    • Lessens your environmental impact on our Earth
    • Handles your business when water is in short supply
    • Solves toilet troubles in places where septic systems are a no-go
    • Gardening benefits and creates compost for your plants ( in around 6-12 months)

What about the disadvantages of a compost toilet?

Naturally, there are a few downsides to a natural compost toilet system:

  • Some toilets that compost do not have a diverter - the addition of liquids into the solid bin can cause bacteria build-up, which causes smells and stops the natural decomposition process. Leading to more regular empties - a difference of at least one month for the solids bin!
  • Smaller portable toilet systems have limited capacity and require a safe place to complete the composting process.
  • If not maintained properly, they could get a little stinky
  • You must manually empty composting toilets when they're full
  • And that’s it!


What is a urine diverter?

Sometimes, you’ll see a special separator inside a compost toilet. This is called a urine diverter or a toilet diverter found in all UDDTs (urine diverting dry toilets). As the name suggests, a urine diverter separates liquids from solids. This is essential in eliminating the sewage smell – and also makes emptying a composting toilet much more pleasant!


How to empty a composting toilet with a urine diverter

As magical as composting toilets may be, someone still has to empty the bathroom situation manually. The frequency depends on the toilet and how many people are using it. A self-contained dry toilet with a urine diverter needs to be emptied when either the liquid or solid container is full. Since these two are separated, you can easily empty either whenever one reaches capacity.

But how do you actually empty a composting toilet? Well, for the liquid chamber, it's best to do it before it's completely full, and the best composting toilets on the market will notify you when the bottle is full to prevent any spillage. You can easily empty the liquid into a bathroom that’s hooked up to a sewer, or you may rid it in the wild so long as it is far enough away from any animals and freshwater sources (at least 200ft).

In most composting toilet systems, you can tell it's time to empty the solids bin when the handle gets tough to turn. A smart tip is to wait about 8 hours after your last bathroom visit before emptying the solid waste chamber. This gives the decomposition process a little head start, and emptying the solid waste bin is quick, easy, and painless. With our Cuddy, you won’t have this issue because we designed a stronger agitator handle, which is pretty easy to turn - so instead, you’ll need to keep an eye on the internal levels.

Always check with certain sanitary restrictions in the area that you are in, but most of the time, human waste is allowed to be thrown away in the garbage, so long as it is tied tightly in a bag. If you live off-grid and wish to use the compost toilet’s contents in your garden, it is best to wait at least 6 months before planting your human manure… or humanure!


What is “Humanure”, and what can I do with compost toilet waste?

Humanure has even more incredible benefits than just its awesome name.

Human manure is a term that refers to when human waste is composted to create nutrient-rich fertilizer, which can be used for agricultural and horticultural purposes. The composting process allows for the decomposition of pathogens and converting toilet waste into a rich and fertile soil conditioner that can enhance soil quality and promote plant growth. It's an environmentally friendly and sustainable approach to managing human waste, often used in ecological or sustainable farming and gardening practices.

Properly managed humanure composting systems can reduce the environmental impact of sewage disposal and contribute to more sustainable agricultural practices.

For more information about humanure and what to do with composting toilet waste, we highly recommend the Humanure Handbook.


How often do you clean a compost toilet?

The answer is far less than you think if you have a split system.

The solids bin should be left as long as possible to allow the microorganisms to do their work, while the liquid bin only needs a little vinegar and water solution or bio-degradable soap when you empty it - a quick shake and you are done. Here’s our cleaning guide for the Cuddy, our product, to show you what we mean.


Where can you install a portable composting toilet?

The beauty of a portable solution is that you can use it wherever you are and in pretty much any situation you feel comfortable.

We’ve had customers install theirs in their RV bathrooms, campervan storage or wet rooms, sailboats, or even in the back of a car, along with a modesty tent for camping trips!


Okay, so what is the best composting toilet?

We may be a bit partial, but we believe Cuddy the Composting Toilet is the best compost toilet system on the market! Cuddy was cleverly designed to fit in the smallest spaces, making it the best toilet option for van life, tiny homes, campervans, and off-grid living. Our composting toilet with urine diverter maximizes convenience, comfort, and usability while minimizing the need to empty often and removing the need for chemicals and wasting water.

So there you have it, folks: everything you need to know to answer the question, “What is a composting toilet?”

Are you ready to jump on the eco-friendly train and make a greener choice today? Cuddy Composting Toilet is your ticket to a more sustainable and environmentally friendly future!


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Richard Peter

Richard is the Co-Founder and CEO of Compocloset, and the mastermind behind the Cuddy Composting toilet.


After a career algorithmic trading, he had plans to follow his long held passion for AI but the pandemic brought about an unexpected twist.


After installing a composting toilet in his campervan he caught the sanitation bug (not the dysentry kind) and saw an opportunity to change the world for the better and help bring safe sanitation to the 2.6 Billion without it. 


He's now on a mission to make the best off-grid toilet possible both for you and the planet! 


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