What is a Composting Toilet

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What is a Composting Toilet
What is a Composting Toilet?

Composting toilets are an innovative alternative to traditional flush-based toilets that treat human waste through a biological process called composting. This eco-friendly option utilizes naturally occurring microorganisms, primarily bacteria and fungi, to decompose organic matter and transform human waste into compost-like material under controlled aerobic conditions. By doing so, composting toilets provide a water-conserving solution to conventional toilets, making them increasingly popular among environmentally conscious individuals.

These composting systems create an oxygen-rich environment that encourages aerobic bacteria to thrive and efficiently break down solid waste. As the waste is combined with carbon-rich materials such as sawdust or peat moss, the process closely mirrors the natural decomposition of leaves into fertilizer. This sustainable waste management method has numerous benefits, including reduced water use, minimized environmental impact, and a welcome addition to garden compost.

Key Takeaways

  • Composting toilets employ a natural, biological process to decompose human waste into a nutrient-rich material.
  • These systems conserve water and promote environmental sustainability by utilizing aerobic bacteria and controlled conditions.
  • There are various types, installations, and brands available to suit different needs and locations, while providing significant ecological benefits.

How Composting Toilets Work

What is a Composting Toilet
Schematic Diagram of a Composting Toilet which shows how composting toilets work

Aerobic Decomposition

Composting toilets rely on aerobic bacteria and other microorganisms to break down human waste using a natural process called aerobic decomposition. To assist these microorganisms, a composting toilet creates an oxygen-rich environment, regulating factors such as heat, moisture, and the carbon-to-nitrogen ratio. This helps to minimize odors and efficiently decompose the waste material into a more benign, compost-like substance.

Urine Diversion Systems

Many composting toilets incorporate urine diversion systems to handle liquid waste separately from solid waste. By doing so, the overall moisture level within the composting system is reduced, enabling aerobic bacteria to be more effective at decomposition. Additionally, this approach helps to prevent excess nitrogen from creating unpleasant odors and slowing down the composting process.

Carbon Additives

A key component of composting toilets is the use of carbon additives as a bulking agent and to help balance the carbon-to-nitrogen ratio. Common materials used for this purpose include sawdust, peat moss, and coconut coir. These materials absorb moisture, ensuring that the composting environment remains suitable for aerobic bacteria, and contribute the necessary carbon for the biological processes.

Types of Composting Toilets

There are two major types of composting toilets: self-contained composting toilets and central system composting toilets. Each plays a role in minimizing water usage and reducing the need for traditional waste disposal systems, while converting human waste into usable compost.

Self-Contained Composting Toilets

Self-contained composting toilets are compact systems that contain all composting components within a single unit. These types of toilets are easily portable and can be installed in various settings such as tiny homes, RVs, and remote locations. When using a self-contained composting toilet, users will typically add carbon-rich materials, like sawdust, peat moss, or coconut coir, to assist in breaking down the waste. Some composting toilets require electricity to run fans and heaters which warm, circulate and ventilate, leading to more efficient composting.

Some advantages of self-contained composting toilets include:

  • Minimal floor space requirements
  • Easy installation and maintenance
  • No need for additional plumbing or sewage connections

However, these systems may not be suitable for very high-traffic areas or large households due to their limited capacity.

Composting Toilets for Tiny Homes
Composting Toilets, like this one by Nature Loo, work well in Tiny Homes

Central System Composting Toilets

Central system composting toilets, sometimes referred to as split systems, consist of a separate composting unit located away from the actual toilet. The waste is transported from the toilet to the composting unit through a pipe or chute system. This type of composting toilet is often beneficial for larger households, public facilities, or settings where a higher volume of waste needs to be managed.

Advantages of central system composting toilets include:

  • Greater waste processing capacity
  • Flexibility in choosing the toilet’s location
  • Better odor management due to remote composting unit

However, installation of central system composting toilets may be more complex and require additional planning.

Both self-contained and central system composting toilets serve as environmentally friendly alternatives to traditional toilets, facilitating responsible waste management practices and conserving water resources. The ideal type of composting toilet depends on factors such as space availability, usage frequency, and desired capacity.

Benefits of Composting Toilets

Composting toilets offer various advantages over traditional toilets, as they address certain environmental and practical concerns. Here are three main benefits: Eco-Friendly, Water Conservation, and Off-Grid Homes.


Composting toilets are considered an eco-friendly option mainly because they don’t rely on chemicals or large quantities of water to handle human waste. Instead, these toilets use aerobic decomposition, which naturally breaks down waste over time. The end product is a nutrient-rich fertilizer that can be used in gardens and landscapes. Additionally, composting toilets generate minimal carbon footprint and help reduce pollution associated with conventional sewage systems.

Water Conservation

One of the most significant advantages of using composting toilets is the considerable amount of water they save. Traditional toilets use between 1.6 to 3.5 gallons of water per flush, which adds up to thousands of gallons per year. In contrast, most composting toilets use little to no water, making them a perfect fit for water conservation efforts. This not only reduces the strain on local water supply but also results in lower water bills, especially in regions where water is a scarce and expensive resource.

Off-Grid Homes

For off-grid homes and remote locations, composting toilets are an ideal choice. Since they don’t require any connection to sewage systems or septic tanks, they allow for easier installation and maintenance in such situations. Moreover, composting toilets typically consume very little electricity, which aligns perfectly with the goals of sustainable living and self-sufficient households. They provide a practical, cost-effective, and environmentally responsible solution for managing human waste in off-grid settings.

Common Locations for Composting Toilets

Composting Toilet on Hilbre Island, Wirral England
Composting Toilet on Local Nature Reserve at Hilbre Island, Wirral England

Residential Use

Composting toilets are increasingly popular in residential use, providing an eco-friendly and water-saving alternative to traditional flushing toilets. They use aerobic decomposition to break down waste without relying on sewage systems, saving water and reducing the environmental impact of waste disposal.

Recreational Vehicles and Boats

In recreational vehicles (RVs) and boats, space and water usage are often limited. Composting toilets are an ideal choice in these settings, providing a compact and efficient solution for waste management. They are portable, easy to maintain, and do not require a connection to a sewer or septic system.

Tiny Homes and Cabins

Tiny homes and cabins, especially those located in remote areas with no access to sewer systems or septic tanks, benefit from composting toilets. They are a sustainable solution for waste disposal, with a significantly smaller footprint and lower water consumption. Composting toilets in these settings can be either self-contained or part of a centralized system, offering flexibility to homeowners.

National Parks

Composting toilets are increasingly used in national parks due to their minimal water usage and positive impact on the environment. They offer a solution that reduces the need for expensive sewage infrastructure and helps conserve water resources. Their low-maintenance requirements and ability to function without harsh chemicals make them a practical choice for preserving our natural landscapes.

Installation and Maintenance

When installing and maintaining a composting toilet, it’s essential to pay attention to proper ventilation systems, heating elements, and moisture level management. These factors play a crucial role in the success of a composting toilet system.

Ventilation Systems

Ventilation is a key aspect of a composting toilet system. Proper ventilation helps manage odors and moisture while providing oxygen to the composting process. To ensure a successful installation:

  • Install a vent pipe to the exterior of the bathroom, following the manufacturer’s instructions
  • Ensure there are no blockages in the vent system
  • Regularly inspect and clean the vent pipes as part of your maintenance tasks

Heating Elements

Heating elements, often found in electric composting toilet systems, aid in evaporating liquids and maintaining the right temperature for composting. To ensure the best performance of the heating elements:

  • Always follow the manufacturer’s instructions for installation and wiring
  • Ensure there is no damage to the heater or its connector cables
  • Regularly check the heater’s performance as part of your maintenance tasks
Central System Composting Toilet
Central System Composting Toilet – Maintenance and Ventilation are Important

Moisture Level Management

Moisture levels play an essential role in the composting process. A balanced moisture level is critical for the effectiveness of the composting toilet system. Here are some tips for managing moisture levels:

  • Add a bulking agent, such as sawdust or coconut coir, to absorb excess moisture and maintain the right balance
  • Use sensors to monitor the moisture level inside the composting chamber
  • If the system has a drainage component, ensure it’s properly connected and maintained

By keeping an eye on these aspects, you can ensure that your composting toilet system functions effectively and efficiently, with minimal odors and a successful composting process.

Materials and Additives

Sawdust and Peat Moss

Sawdust and peat moss are commonly used materials in composting toilets as they are rich in carbon, which helps with the decomposition process. Adding these materials to the toilet not only controls odor but also balances the moisture levels in the waste. Sawdust, a byproduct of the lumber industry, is readily available and cost-effective. Peat moss, on the other hand, is obtained from natural wetlands and has an excellent moisture-absorbing capacity.

Coconut Coir

Coconut coir is another suitable material for composting toilets. Derived from the tough fibers found in coconut husks, this eco-friendly product is both renewable and biodegradable. Like sawdust and peat moss, coconut coir serves as a carbon-rich additive, effectively managing odors and moisture levels in the waste. Moreover, coconut coir has a fibrous texture, improving aeration and promoting faster decomposition.

Toilet Paper

Toilet paper can also be incorporated into composting toilets, as it contributes to the balance of organic matter. Since it’s made from plant fibers, toilet paper decomposes easily and adds a small amount of carbon to the mix. When using toilet paper in a composting toilet, choose a biodegradable, eco-friendly, and fragrance-free option, as these characteristics contribute to a more efficient decomposition process.

Regulations and Environmental Impact

Composting toilets are a type of wastewater treatment system that use little or no water and generally do not require hookup to a sewer or septic system. They treat human waste by a biological process called composting, which leads to the decomposition of organic matter and turns human waste into compost-like material. This process has a positive environmental impact since it saves water and avoids the need for harmful chemicals in sewage treatment.

In terms of regulation, composting toilets are subject to building codes and environmental laws in many jurisdictions. Generally, they are allowed in residential spaces, but it is essential to check with your local authorities and comply with any specific requirements. One common regulation in the United States is that composting toilets must meet the requirements of NSF Standard 41, which governs the design and construction of these systems.

The Environmental Protection Agency (EPA) supports the use of composting toilets as they contribute to reducing water consumption and minimizing the environmental impact of waste disposal. By not requiring connection to a septic tank or sewer system, composting toilets can help improve the overall sustainability and autonomy of a household.

It is worth noting that composting toilets may only be utilized in conjunction with an approved gray water treatment and disposal system. Gray water is wastewater generated from household activities such as bathing and washing, which is distinct from black water produced by composting toilets. Both types of wastewater must be dealt with responsibly to protect public health and the environment.

In conclusion, composting toilets present a viable and eco-friendly alternative to traditional toilets. However, one must consider the applicable regulations and strive to comply with building codes and environmental laws when installing and operating these systems.

Video – What is a Composting Toilet?

A thorough guide to what a composting toilet is and what its like to live with one.

What is a composting Toilet Video

Below is a summary of the top manufactures of composting toilets. For our take on the best composting toilets, see this article.

Nature’s Head

Nature’s Head is a popular brand known for its reliable and high-quality composting toilets. These toilets are designed to handle human waste in an environmentally friendly way. They separate solid and liquid waste, which helps control odor and promotes the composting process. Nature’s Head toilets are often utilized in off-grid locations, boats, and tiny homes.

Their composting toilets are portable, making them a convenient solution for various situations. The Nature’s Head Self-Contained Composting Toilet is one of their popular models and is priced at around $960. This model features a comfortable design and is easy to maintain.


Separett is another well-known brand in the world of composting toilets. They offer a range of models, catering to different needs and preferences. Separett toilets also separate liquid and solid waste for an odor-free experience and efficient composting. Their toilets are suitable for both permanent and portable applications.

Among Separett’s offerings, the Separett Villa 9215 AC/DC is a popular choice, priced at approximately $1,400. This model is designed for both on-grid and off-grid use, providing versatility for different lifestyles. You can see how the Separett Villa compares to the Dry Flush Laveo here.

Home Depot

The Home Depot is a one-stop-shop for various home improvement needs, including composting toilets. They carry brands like Sun-Mar, which provide compact and non-electric options suitable for off-grid living or recreational situations. The Home Depot offers different models catering to a wide range of budgets.

For instance, the Sun-Mar Compact Composting Toilet is available at The Home Depot for around $1,750. This model is easy to maintain and provides an odor-free experience. The store also offers portable composting toilets for those who require a temporary or mobile solution. One such example is the Boxio Portable Composting Camping Toilet, which has a relatively lower price.

In conclusion, composting toilets are an environmentally friendly alternative to traditional toilets, and there are several popular brands in the market. Nature’s Head and Separett offer high-quality composting toilets while Home Depot provides a variety of options to cater to different budgets and needs.

Frequently Asked Questions

How do composting toilets work?

Composting toilets use aerobic decomposition to break down human waste instead of flushing it away in watery sewage. These toilets are water-less and turn waste into safe and usable compost. The composting process involves the waste being stored and requires someone to regularly turn or spin it to help the composting process along.

Are composting toilets odor-free?

When properly maintained, composting toilets should not produce any unpleasant odors. Proper ventilation and the use of bulking materials, such as sawdust, can help control and eliminate odors, making it a comfortable and eco-friendly alternative to traditional toilets.

How often do you empty a composting toilet?

The frequency of emptying a composting toilet depends on the specific design and usage. Some units need to be emptied every few months, while others may only require emptying once or twice a year. Monitoring the level of the compost and regular maintenance are crucial to ensure optimal performance and timely emptying.

Is a composting toilet suitable for a tiny house?

Yes, composting toilets are particularly popular in the tiny house community, as they are compact, water-less, and environmentally friendly. Their water-saving feature makes them an excellent choice for those living off-grid or in areas with water restrictions.

Can composting toilets handle diarrhea?

Composting toilets are designed to handle both solid and liquid waste. In the case of diarrhea, the toilet will still process the waste effectively. However, the addition of extra bulking material and proper maintenance can ensure the composting process continues without issues.

What is the process for disposing of composting toilet waste?

Once the waste has been composted and is ready to be removed from the toilet, it can be disposed of or used as a soil conditioner or fertilizer for non-edible plants, such as flowerbeds or ornamental gardens. It is important to follow local regulations regarding the disposal of composted waste and verify that the compost has reached a safe level of decomposition before application.

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