How a Composting Toilet Works: Behind the Scenes (2024)

how does a composting toilet work

The question “how does a composting toilet work” raises the curiosity of many. As we turn our focus towards greener solutions and water-saving measures, understanding the inner workings of eco-friendly alternatives becomes not just fascinating but vital.

Composting toilets present a unique blend of simplicity and science. They are a testament to how ingenious methods can transform everyday processes into something more environmentally friendly. By learning about how these composting toilets work, we uncover a key piece of the puzzle in our quest for a sustainable future.

Essentially, composting toilets operate on a straightforward principle. Waste, whether liquid or solid, is deposited into the toilet. Following this, a carbon-rich substance, often sawdust, is added. This mixture creates the perfect environment for natural processes to break down the waste, turning it into a harmless, nutrient-rich compost for soil enrichment.

Learning more about the composting toilet system and its functionality can raise your awareness of another renewable waste alternative available. 

In this article, I will exactly cover these key aspects of a compost toilet.

  • The definition and concept of compost toilets
  • Various components that make up a composting toilet
  • Suitable materials for disposal in the toilet
  • Fundamental maintenance requirements for a composting toilet
  • Determining the best type of composting toilet for your needs
  • Common advantages associated with using composting toilets

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What is a Composting Toilet?

A composting toilet is a type of toilet that treats human waste through a biological process known as composting. 

This process breaks down waste into simpler, harmless organic compounds. 

Unlike traditional toilets, composting toilets do not require water for flushing and are designed to convert waste into usable compost. 

They are particularly effective in areas without access to water or sewage systems and are valued for their low environmental impact.

Parts of the Composting Toilet – How Does a Composting Toilet Work

image of composting toilet-how does a composting toilet work

A composting toilet, a practical solution for waste management, comprises several key components that work together efficiently. At its core, the design includes:

  • A urine separator is an insert that divides liquid waste from solid waste.
  • A container or bucket for solid waste, often lined with a compostable bag for ease of handling.
  • A separate canister for urine collection could alternatively be connected to a larger tank via a hose.
  • An enclosure that houses these elements, topped with a regular toilet seat for comfort.
  • An electric fan is used in some models to help with odor and composting control.

The way these parts function is straightforward yet effective. Solid waste is collected in a rear bucket, while liquid waste is directed to a front canister. The solids container and urine canister can be emptied independently, facilitating easy waste management.

It’s worth noting that composting toilets differ from what are sometimes referred to as a dry toilet. Dry toilets do not separate liquid and solid waste, collecting both in a single container. This method can lead to some of the issues composting toilets are designed to avoid, which is why the separation system is generally preferred for its efficiency and hygienic advantages.

Creating your own DIY Composting Toilet is not as hard as you might think. In fact, if you know how to use some basic tools, you can do this. 

The operation of a composting toilet

This involves a simple, user-friendly process.

  1. Start with Separation: As you use the toilet, you’ll notice the urine separator at work. It cleverly directs liquid waste into one container and solid waste into another, playing a crucial role in keeping odors at bay.
  2. Add Carbon-Rich Material: After each use, it’s your turn to add a scoop of carbon-rich material, like sawdust, peat moss, or coco coir into the solid waste container. This simple action helps absorb moisture and keeps smells under control, making the process hygienic and hassle-free.
  3. Mixing: If your toilet has a mixing mechanism, such as a rotating drum or a crank, use it to mix the waste with the bulking material. This helps with odor control and ensures even decomposition. This step is typically done about three times a week for daily usage.
  4. Emptying the Toilet: One of the best parts? There’s no need for flushing or harsh chemicals. When the containers are full, you just empty them separately, following local guidelines for waste disposal. This step is straightforward and supports a greener lifestyle.
  5. Clean up for Odor Control: Clean up any spills or messes as needed. Some people keep a spray bottle with a water and vinegar solution handy for cleaning. If there’s a smell, you can add sugar or vinegar to the liquid waste to neutralize odors.

A Composting Does Not Require Water – Why?

how does a composting toilet work

A composting toilet stands out for its eco-friendliness, primarily because it operates without the need for water. This is a significant advantage, considering that traditional flushing toilets can account for up to 30% of a household’s water consumption. 

By choosing a composting toilet, you’re not only saving water but also reducing the environmental impact associated with wastewater treatment, which typically involves electricity and chemicals.

Composting toilets are beneficial in scenarios where water availability is limited or where conventional plumbing is impractical, such as in remote cabins or off-grid living situations. The absence of water in the composting process means these composting toilets work similarly and can be set up in a variety of settings without the need for extensive plumbing infrastructure.

What Material Should I Use Inside the Toilet?

what materials are best for composting toilet

When using a composting toilet, selecting the right material to add to the waste is crucial for efficient composting. 

Commonly used materials include coconut coir, sawdust, peat moss, or wood chips. These types of littler material creates air pockets in the waste, promoting aerobic decomposition, and helping to control odor. The choice of material can depend on various factors like availability, environmental impact, and personal preference.

Each of these materials has its advantages. 

For instance, coconut coir is highly absorbent and effective, and its increased availability makes it a popular choice.

Sawdust is another common option, known for its affordability and effectiveness in absorbing waste. 

Peat moss, while effective, is less environmentally sustainable due to its long formation time and the ecological impact of its extraction. 

Wood chips are also effective, particularly in their ability to absorb waste without significant downsides.

In choosing the material for your composting toilet, in my opinion, it might be helpful to try out a few different types to see which works best for you and your system.

Composting Toilet Maintenace – What it Takes

Maintaining a composting toilet is straightforward and doesn’t require extensive effort. Here are the key steps:

  • Empty Regularly: Depending on usage, clear out liquid waste every few days and solid waste every few weeks.
  • Maintain Moisture Level: Ensure the compost isn’t too dry or too wet. Adjust by adding dry material or a bit of water.
  • Add Carbon Material: After each use, add carbon-rich material like sawdust to aid in composting and control odors.
  • Clean Gently: Use natural cleaning solutions for routine cleaning, avoiding harsh chemicals.
  • Check for Odors: Good ventilation and correct compost balance should minimize smells. If odors persist, review your maintenance routine.

Interested in learning more? Visit my detailed article focused on composting toilet upkeep. It’s packed with actionable and friendly advice for maintaining your composting toilet effectively, and includes many more insights!

Which Composting Toilet is Right for You?

Selecting the right composting toilet boils down to understanding the two main types available.  Most composting toilets are self-contained composting toilets and central (or split system) composting toilets.

Self-Contained Composting Toilets – Most Common 

Ideal for smaller spaces or individual use, these toilets house both the toilet and the composting unit in one compact design. They are particularly suitable for places without easy access to an external composting site, like small homes, RVs, or boats. 

If you prefer a straightforward, easy-to-install solution, this might be the right choice for you.

Central Composting Toilets – Suitable for More Users

These are more extensive systems where the toilet is separate from the composting unit. The composting unit is typically located beneath the bathroom or outside the building. This type is ideal for larger homes or buildings with multiple toilets. 

Centralized systems can handle a larger volume of waste, making them a good fit for families or shared spaces.

For a thorough rundown of the best composting toilets, my guide breaks down the top models for you.

Benefits of Composting Toilets

Environmental Benefits

Composting toilets are a win for the environment. They significantly reduce the need for water and energy typically used in conventional sewage treatment. By transforming waste into compost, they also contribute to the nutrient cycle, returning valuable organic matter back to the earth.

Water Saving Measures

One of the standout advantages of composting toilets is their minimal water usage. Unlike traditional toile, composting toilets offer a sustainable solution when water is scarce. They’re especially beneficial in areas where water resources are limited or for people aiming to reduce their ecological footprint.

Healthier Gardens

The compost produced by these toilets can be a boon for gardens. It’s a nutrient-rich, natural fertilizer that enhances soil quality, promoting healthier plant growth. This not only benefits your garden but also contributes to broader ecological health by reducing the need for chemical fertilizers.


Composting toilets offer an eco-friendly alternative to traditional toilets, reducing water usage and providing a sustainable solution for waste management. 

While they come with some unique maintenance requirements, understanding these systems can lead to a more environmentally conscious and cost-effective lifestyle.

If you plan on going off the grid and doing your research beforehand, this article is a great place to start. 

Frequently Asked Questions

What are the drawbacks of a composting toilet?

Composting toilets can require more hands-on maintenance than traditional toilets, including regular emptying and balancing of compost material. They may also have a higher initial cost, and some people might find the concept less appealing.

How do you empty a composting toilet?

To empty a composting toilet, remove the container holding the waste. Liquid waste should be emptied more frequently, often every few days, while solid waste can typically be emptied every few weeks, depending on usage.

Where does the waste go in a composting toilet?

In a composting toilet, waste is separated into liquid and solid compartments. Solid waste is treated with bulking agents like sawdust or peat moss to aid decomposition, while liquid waste is often separately managed or evaporated.

How often do you need to empty a composting toilet?

The frequency of emptying a composting toilet varies based on usage and the model of the toilet. Generally, liquid waste needs to be emptied every few days, while solid waste can be emptied every few weeks.

Typically what I’ve seen, 2-4 regular users, it’s common to empty the solids compartment of the composting toilet every 2-4 weeks

What happens if you have diarrhea in a composting toilet?

In cases of diarrhea, you may need to add more bulking material to manage the additional liquid and maintain the balance required for effective composting. 

You do not want your compost too wet here so add enough coco coir, peat moss, or wood chips to help with the moisture.  

Can you throw toilet paper in a composting toilet?

Yes, you can throw toilet paper in a composting toilet. It will decompose along with the waste. However, it’s advisable to use toilet paper that breaks down easily to avoid potential composting issues.

Is it ok to urinate in a composting toilet?

Yes, it is ok to urinate in a composting toilet. These toilets are designed to handle both liquid and solid human waste. In many models, urine is diverted to a separate urine tank to aid in the composting process.

Dry toilets however usually have one main compartment that collects both your solids and liquids. In this case, using more material agents would help with the composting process.

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