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Composting Toilets: What They Are + Top Picks for 2024

Composting Toilet

Flushing dozens of gallons of water down your toilets every day can make you think twice about how much you spend on your water bill each month, how much water you are actually using, and how much you may be wasting.

If you have ever worried about these things, a composting toilet may be a possible solution. Keep reading to learn about all the different aspects of composting toilets and how they work.

What is a Composting Toilet?

A composting toilet is typically a waterless system that uses decomposition and evaporation to recycle human waste. It’s not an outhouse or even a port-o-potty, but a physical toilet that can convert solid waste into compost through the composting process.

Not only do they compost human waste, but also toilet paper while still remaining odorless. They do this by creating an oxygen-rich environment that enables aerobic bacteria to break down the waste.

They can be a great option for just about everyone since they come in different sizes, systems, and tank capacities. Composting toilets are particularly great for tiny homes, cabins, those living off the grid, and many also use them in their RVs.

But that’s not all, you can even have multiple in your own home, all connected to a single system. Fortunately, there is a variety of them on the market! Let’s first understand the different types of composting toilets, and then see what you need to consider before getting one (or many even two or more!).

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Two Main Types of Composting Toilets

Composting toilets usually fall into two different categories: a self-contained composting unit and a central composting toilet system. Let’s look at each of them in more detail:

Self-Contained System

Self-contained composting toilets can be directly installed and have the entire composting system housed inside of the toilet. The composting chamber in this case can be found and emptied directly beneath the toilet and comes with a liquid drain for removing waste.

Some of these are portable, which makes them a great choice for camping trips or even boat rides. Since they’re portable, they can be set up anywhere where plumping won’t reach, e.g. a garage or workshop.

Split or Central System

A central composting toilet system has two parts. The first is the toilet itself, and the second is a composting chamber that is located in the basement or outside of the building where the solid, and sometimes even liquid waste is directed to.

These systems usually have larger composting capacities, as they require a hopper that’s installed usually below the toilet. Another benefit to split systems is that these toilets usually look more like a traditional septic tank or compost pile and can ease peoples’ anxiety over the aesthetics of toilets that are less appealing.

These systems are great for permanent off-grid or eco-conscious homes, but they’re not as portable due to the setup.

How Does a Composting Toilet Work?

A composting toilet works by centering around the main action of separating liquids from solids without needing to flush. These different forms of waste are moved to different chambers to either a location somewhere in the basement or outside using a hand crank or some other composting toilet system.

Liquid waste (urine) moves into an evaporating chamber. This evaporating chamber contains various aerobic organisms such as bacteria, fungi, compost worms, or other tiny insects. These organisms help enrich the urine with nitrogen which allows it to evaporate faster. This nitrogen-enriched liquid can then be used as fertilizer for crops or plants.

Solid waste is moved into a chamber separate from the liquid chamber. This chamber also holds aerobic organisms similar to those in the liquid waste chamber.

However, a small amount of carbon material must also be placed in this chamber. The absorbent material helps the solid waste break down more quickly and effectively into dry compost material. Examples of these materials include wood chips, peat moss, ash straw, or sawdust.

The most important conditions to monitor in composting toilets are oxygen levels, aeration, temperature, carbon materials, and aerobic organisms. All of these components must be working actively in order to ensure that waste is broken down.

Is a Composting Toilet Worth It?

Composting toilets are worth it if you are after a few of these advantages:

  • Reducing dependence on traditional plumbing
  • Reducing wastewater use
  • Reducing impact on the environment
  • Creating compost for plants
  • Solution for settings where septic systems aren’t available or when plumbing is not available
  • Solution for when water is scarce
  • Saving money

What are the Disadvantages of a Composting Toilet?

Most people are turned off by the idea of composting toilets because of their appearance. They are not always the most aesthetically pleasing. Fortunately, this problem can be solved by choosing designs that are more similar to the appearance of traditional toilets.

Other than appearance, a few disadvantages include:

  • The need to manually remove the waste whenever the toilet is full
  • Smaller systems have limited capacity
  • Composting systems that are not installed well can produce an odor

For the most part, however, most people do not find too many large issues when it comes to using a composting toilet.

Different Components of a Composting Toilet

Composting toilets have several different components: the toilet unit and the collection unit which is made up of two different chambers (composting chamber and aeration unit).

Let’s look at each of these in more detail to understand how they work together:


This is the unit that is familiar to everyone because it resembles the toilet seat that you would find regularly. The main purpose this serves is as a comfortable seat for you to position yourself and excrete waste from your body.

Collection Unit

This is where the waste breakdown and evaporation processes take place. This component itself has two different chambers:

Composting Chamber: This chamber stores the waste so that it can decompose properly. It is usually designed so that liquid and solid waste are easily separated.

Aeration Unit: This unit maximizes efficient decomposition of solid and liquid waste. It is designed to maintain oxygen, aeration, and temperature levels.

What to Consider When Buying a Composting Toilet

Available Space

As opposed to conventional toilets, composting toilets require a little bit more floor space and don’t require a separate holding tank. Consider a compact composting toilet with a smaller waste tank for a tiny house or boat.

If there is room for a split system, it might be worthwhile to spend the extra money to get the bigger holding capacity.

Tank Capacity

When looking for the best composting toilet, consider how many people will be using it. This will determine the size of the tank required. Manufacturers frequently categorize this based on family size and intended use.

A split system with a large tank, for example, could handle waste from three adults or a family of five, whereas a self-contained composting toilet with a five-gallon tank would be sufficient for one adult.

The goal here is to make sure that waste has sufficient time to decompose into manure before the tank is completely full.

Energy and Water Usage

Some composting toilets require the use of electricity in order to power a fan that circulates air throughout the tank and over the waste.

The oxygen-rich air feeds the aerobic bacteria that break down the waste. Additionally, the air is vented with the help of this, exchanging the carbon dioxide the bacteria produced.

A water line may also be required for a composting toilet. Although it may seem counterintuitive, composting toilets that use water consume significantly less water per flush than conventional residential toilets.

There are also waterless and non-electric models available, so when selecting the best toilet, take your household’s utility setup and budget into account.

Odor Removal

The bacteria in a composting toilet produce gases that must be vented. If not, smells could build up, or the bacteria might not work as well because they don’t have enough fresh air.

Since some models use a fan to pull air into the tank, this fan also forces the gases out of the tank through the vent, getting rid of any bad smells in the process.

After each use, you can reduce odor while still allowing bacteria to break down the solids by covering the waste with organic materials like sawdust.

NSF Certification

Even though there is no organization that sets functional requirements for composting toilets, some manufacturers seek certification from this independent third-party organization.

This organization checks that consumer products meet basic standards, such as being odorless or being able to handle the advertised capacity.

Top 3 Best Composting Toilets in 2022

In true Planet Natural fashion, we want to provide you with just about everything you’ll need to have your own composting toilet system. Here are our top three picks:

1. Nature’s Head Self-Contained Composting Toilet

Nature’s Head has the best and one of the most easy-to-use composting toilets on the market. It comes with a spider handle that allows you to churn solid waste inside the tank.

Plus, it also diverts urine into a separate tank that can be easily removed. This is a great composting toilet for anyone looking to buy their first one!

The waste tank is big enough for two adults to use full-time. With this type of usage, you’ll need to empty it out every four to six weeks.

It also comes with an electric can that not only draws fresh air in to feed the bacteria, but also draws odor out to help keep any smells at bay.

Natures Head Self Contained Composting Toilet

Natures Head Self Contained Composting Toilet

2. Sun-Mar Excel Composting Toilet

This is another great choice by the brand Sun-Mar. It’s large enough for three to four adults to use for 6-8 weekends, and it comes with an electric fan to dry liquids! The fan also helps draw air in and push odor out, which helps keep it odorless and easy to manage.

This was also the first ever self-containing composting toilet that got certified by National Sanitation Foundation (NSF), so you can rest assured that the quality is great and meets the standard.

3. Separett Villa 9215 AC/DC Composting Toilet

This is definitely the best compact composting toilet on the market, and features a waterless self-contained design that also comes with an electric fan.

It’s a lightweight composting toilet, that weighs just 34 pounds and is also smaller in size making it quite portable.

The kit comes with adapters for both 110V and 12V, and even includes all the parts you’ll need for direct venting and to connect the liquid drain to a gray water system.

Despite its small, portable design, it’s large enough for 3 weeks of use for an average family. You can even buy a child seat accessory separately!

Separett Villa 9215 Composting Toilet

Separett Villa 9215 Composting Toilet

How Much Does It Cost to Install a Composting Toilet?

Costs of composting toilets vary depending on installation and the toilet itself. This can range for $50 for a do-it-yourself installation to the thousands for advanced composting toilets with special features or for commercial composting toilets.

Added features that can incur higher costs include electric options, heating elements, or sensors. For do-it-yourself installations, there are many resources online for those interested in building their own composting toilet.

Keep in mind you will need to have a personal, outdoor composting bin ready to go before installing the toilet.

Do You Have to Empty a Composting Toilet?

Yes! Composting toilets must be emptied when they are full. The frequency can vary depending on household size and usage, as well as the type of composting toilet that you have. A self-contained composting toilet, for example, needs to be emptied whenever the liquid or solid container is full.

A traditional house with central compost systems needs their chambers emptied less often. A house of 3-4 persons with typical usage might not have to empty out their composting chamber until after about a year of use. In warmer weather some people will empty their chambers after the winter to ensure that waste is completely decomposed.

How Do You Empty a Composting Toilet?

It is suggested that people empty their liquid chambers before they are completely full. For a 2 gallon tank, this can mean emptying every 3-4 days depending on frequency of usage. All you need to do to empty the liquid chamber is to remove the liquid tank, cap it, and dispose of the liquid.

When it comes to solids, you can judge when to empty by how difficult it is to turn the base handle. You can also tell when it is time to dump the solid waste compost when it looks and smells like dirt.

A good tip is to wait eight hours after your last bathroom visit before emptying the solid waste chamber. This allows the decomposition process some time to occur before emptying. Solid waste chamber changes are quick, easy, and painless.

Ensure the liquid tank is capped so nothing spills. Unplug any cords and take the toilet outside. Remove the lid and cover the toilet base with a trash bag.

After you are done emptying, you can place the toilet back in place. Any leftover waste still clinging to the sides will help begin the next round of composting.

To summarize, here is how to empty your composting toilet:

  1. Wait 8 hours after your last use of the toilet before emptying.
  2. Make sure the liquid tank is capped so that it doesn’t spill.
  3. Unplug the cords and take it outside.
  4. Remove the lid and cover the toilet base with a trash bag.
  5. After you are done, return the toilet to its spot

Other Frequently Asked Questions for Composting Toilets

How To Use a Composting Toilet?

Composting toilets can be used like regular toilets. With solid waste, be sure to turn the handle at the base to “flush” any solid excrement. If the bowl gets dirty, you can use a vinegar and water mixture spray to help keep it clean. Other than that, it just requires emptying whenever it is full.

How Does Moisture Affect a Composting Toilet?

Because too much moisture in the waste can drown the oxygen-breathing aerobic bacteria, composting toilets come equipped with urine-diverting mechanisms. Too much moisture can create a gap in the decomposition process and prevent waste from being broken down as quickly and efficiently as usual.

What Helps Keep the Carbon-Nitrogen Balance in a Composting Toilet?

Composting toilets must maintain a healthy balance of nitrogen and carbon to keep the bacteria thriving. Making sure to empty the nitrogen-rich liquid waste will ensure this balance. In addition, carbon material can be added to offset the balance. This includes materials like sawdust, peat, or coconut fiber.

What Temperature Should the Composting Toilet Be Kept At?

Composting aerobic bacteria stops working when the weather becomes too cold. It is recommended that the ideal temperature range for a composting toilet to work efficiently is between 60 and 100 degrees Fahrenheit. Some composting toilets come with additional features like thermostats and sensors that help the owner keep track of the composting toilet’s conditions.

Do Composting Toilets Smell Bad?

Surprisingly, composting toilets smell less than regular toilets. This is because the separation of liquid and solid wastes prevents the sewer smell that can occur with water flush toilets.

Composting toilets can have built-in fans that create a vacuum to carry out bad odors and are created with specifications of an enclosed containment system, meaning the only smell you should notice is fresh dirt and not waste smells.

Additionally, carbon materials that you add to your composting toilet like sawdust or peat encourage aerobic bacteria breakdown of waste into odorless compounds.

Is It Okay to Have Maggots in My Compost?

Maggots will not hurt compost, but they can be a signal that there is something off about your materials. Not to mention, maggots can be annoying pests.

Compost does not produce flies, so ensure that any holes are covered and the lid is kept closed to prevent flies from getting to the compost and laying eggs. You can also try adding more brown material to create a dryer environment.

Maggots in compost will eventually die and decompose. Those that do not can be removed with a thorough cleaning or with the use of neem oil. In the meantime, don’t worry, as they can be helpful in speeding up decomposition processes.

Where Does Toilet Paper Go in a Composting Toilet?

Toilet paper can be thrown into composting toilets just as it is tossed into water flush toilets. Since paper products decompose at a slower rate than solid wastes, you will still see pieces of toilet paper in any compost you are emptying.

This is okay. Just remember not to throw diapers, wipes, tampons, and pads into the composting toilet.

Can Composting Toilets Be Used in the Cold?

Decomposition processes slow down significantly in colder climates. This does not mean that composting toilets are not an option. In cases of cold weather, a hot compost bin outside can resolve this problem.

In addition, many composting toilets can be heated or insulated to keep the decomposition process active.

Do You Need to Have a Septic System When You Have a Composting Toilet?

Composting toilets do not need to be connected to a septic system or sewer system. This is why composting toilets are ideal for those that are off grid or in areas where septic systems are not available.

Common usages of composting toilets are in national parks, remote homes, or rural areas in developing countries specifically for the convenience it provides in not needing a septic system.

Where Should I Empty a Composting Toilet?

If you don’t want to use your compost for your lawn and garden, contact your local code enforcement agency about disposal.

Are There Any Regulations Regarding Composting Toilets?

Make sure to contact your local health department and check with them about state and local regulations regarding composting toilets before installing one.

Some states require composting toilets to be certified and have specific guidelines for building composting toilets. Many times, people can have composting toilets in their homes as long as the following conditions are met:

  • There is one toilet connected to a septic system
  • The toilet doesn’t transport their waste across lines
  • The toilet is not a nuisance to neighbors or community as a whole.

Ready to invest in a greener future today? A composting toilet may just be for you!


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