What is a Composting Toilet?

A composting toilet is a type of toilet that converts solid waste into compost. It does this through a biological process which decomposes organic matter into a compost-like material. These toilets are typically ‘dry’, which means they don’t require water for flushing.

Composting toilets are often used in areas that lack an adequate water supply or sewers, and come in two different designs.

How Do Composting Toilets Work?

Composting toilets collect both liquid and solid waste in a well-sealed chamber, located under the pedestal of the toilet. This chamber contains the microorganisms necessary to decompose the waste.

Roughly about three quarters of the waste is converted to water vapor and carbon dioxide which is removed from the pile through aeration.

The rest of the compost then moves down into another chamber by gravity, as more material is added to it. It stays in this chamber until it’s ready to be removed. It can be removed for use ever 2-3 months or once year. The excess liquids and leachate from the compost pile are absorbed into a trench.

All composting toilets work the same way, regardless of whether they use a central or self-contained system. They maintain the right balance between carbon and nitrogen, level of moisture and temperature for the aerobic bacteria to do its work: turning waste into compost.

The following factors have to be considered when maintaining a composting toilet.

1. Controlling Moisture

If there’s too much moisture in the compost chamber, the aerobic bacteria (bacteria that requires oxygen to survive) will be drowned and the process will not be successful. Therefore, it’s important to keep the compost pile moist, not wet.

The toilet does this by diverting urine into a separate container that must be emptied when full. It also dries up the solid waste with the use of a fan that keeps the air circulating. Since solid waste contains a lot of water, the fan-assisted ventilation process reduced the volume of the waste by around 95%.

2. Maintaining Temperature

In order to keep the bacteria alive, it’s important to maintain the right temperature which is usually between 60-100 degrees Fahrenheit.

The bacteria tend to generate heat as they work, and this heat is held in the compost. If the heat is lost, it would be too wet and the process would be disturbed.

Heat causes the pathogenic microbes in the waste to be destroyed which is what makes the end product safe. 

3. Balancing Carbon and Nitrogen

When the urine is disposed of properly, it prevents the buildup of excess nitrogen in the compost.

However, it’s important to add materials rich in carbon to the pile in order to maintain the balance between the two. Some systems use coconut fiber and peat while others use sawdust.

Two Main Types of Composting Toilets

While there can be different designs when it comes to composting toilets. However, these all fall into two main types.

1. Self-Contained Toilets

compost toilets

These toilets come with a detachable tank and a drain to remove liquid waste. The entire system consists of a single unit, and due to its portability, it’s commonly used in boats, RVs, small homes or wherever plumbing can’t be installed.

Although they’re sometimes used in cabins and cottages, not all models can handle full-time use which is why they’re not commonly found in bigger households.

2. Central (or Remote) Toilets

a centralized compost toilet

Central composting toilets, unlike the self-contained models, are usually used full-time in houses and other buildings.  These toilets are connected to a system of pipes that direct both solid and liquid waste to a central composter which is placed in another location, either in the basement or outside.

Unlike the self-contained toilet system, the central system can connect several toilets to one composter, making it ideal for large households. The central system is made to look and feel just like a conventional toilet. It’s much more expensive than the self-contained models since it has a tank that’s installed just below it.

Components of a Composting Toilet

All composting toilets have the same basic components:

  1. The Compost Chamber: This is where the waste and the composting additives are mixed together for the process to begin.
  2. Ventilation: This provides aeration which is important to promote the growth of aerobic bacteria.
  3. Exhaust system: Works to remove heat, gases and odors during the decomposing process.
  4. A way to manage leachate and excess liquid. This is optional.
  5. A way to withdraw the compost once it’s ready.

Types of Composting Toilets

As already mentioned, although there are several types of composting toilets on the market, they all fall into central or self-contained systems. Here are the most common types in use today:

1. Electric Composting Toilet

These toilets use electricity to speed up the composting process. Some have a small electrical fan inside the compost chamber which causes air to continuously flow through the ventilation line.

2. Dry Composting Toilet

This type uses no water. Some are designed to look and feel like traditional toilets by using water for flushing, but they use only about 1 pint or less for each flush.

3. Portable Composting Toilet

This model is used for camping or on vehicles such as trains, RVs or boats. They can easily be moved around and are self-contained.

4. Solar Composting Toilet

In this toilet, there’s no need to separate the solid waste from the liquid. All the waste is collected in it and then emptied into a composting tank  placed outside in the sun. The tank is solar assisted and uses the heat from the sun to keep the microbes at a higher temperature to speed up the composting process. The advantage of solar models is they eliminate the need for batteries for the fan, unlike electric toilets. Many composting toilets nowadays come with the accessories necessary for converting them to solar.

Pros and Cons of a Composting Toilet

Composting toilets come with many advantages, especially when it comes to water and energy consumption. However, they also have their downsides.


  1. An average family can save up to 30,000 liters of water per year.
  2. The toilet can be connected to a solar panel in order to run its exhaust fan, reducing or completing eliminating energy consumption.
  3. Once the toilet is installed, there’s minimal ongoing cost.
  4. These toilets are environmentally friendly.
  5. Installing a composting toilet costs far less than a traditional toilet.
  6. These toilets have few moving parts, which means there’s less maintenance involved.
  7. If properly maintained, there will be no unpleasant odors.
  8. They take up very little space. If you have a central system, most of the system will be placed in the dead space of your house.


  1. Since the waste is not flushed away, manual handling of the composted waste is necessary.
  2. Unlike traditional flush toilets that do not require power, composting toilets use a small amount of electricity to run the exhaust fan.
  3. The initial cost for a composting toilet is higher than traditional toilets.
  4. Maintenance involves handling human waste.
  5. If the toilet isn’t maintained well, it can smell bad.

Composting Toilet FAQs

Whether you’ve already bought a composting toilet or you’re still considering it, you probably have a lot of questions about how to use and maintain one. Here are some of the most frequently asked questions about composting toilets.

  • Do composting toilets smell bad? No. People normally tend to assume that a compost toilet would smell band, stinking up the entire house. However, there is hardly any odor at all. The little smell that you would get is much like the smell of mulch or wood.
  • Can I use toilet paper or tissue in a compost toilet? You can use any type of toilet paper (single ply breaks down faster) or tissue for a composting toilet since it can break it down along with the human waste.
  • Should the ventilation fan run all the time? If the toilet is being used full time, it would be necessary to keep the fan on permanently. This speeds up the composting process. However, if you won’t be using the toilet for several days, unplug it and empty the solid waste bin and the urine bottle (if it has one) before leaving the toilet.
  • How can I dispose of the compostable material? The compostable material can be throwing in the trash if you don’t plan to use it. Otherwise, you can put it into a compost pile so that it can finish composting.
  • Can I use a composting toilet in freezing conditions? The composting process will work from 55 degrees and above.  
  • Do compost toilets require electricity? Most compost toilets require electricity for the fan to function. Some work on battery power while others can be plugged directly to wall plugin.
  • How often do you need to empty a composting toilet? Composting toilets used for commercial purposes need to be emptied once every 3 months because the composting chamber will most likely be full of waste by this time.
  • What is the best cover material to use in a composting toilet?  You can use any of the following: coconut coir, peat moss, wood shavings, sawdust, chopped straw, leaves, grass clippings, pine needles or soil.

The Bottom Line

Composting toilets are quickly gaining popularity due to their many benefits and ease of use. If you’re looking to save money on energy and water while minimizing your environmental footprint, adding a compost toilet to the system you currently use or plan to use in the future would be a wise and rewarding choice. They’re excellent options for mobile homes, campervans, tiny homes, and other similar situations. 

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