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How Does a Composting Toilet Work? 2023

In this blog post, I’ll explain everything you need to know about composting toilet systems, how they operate, and their benefits. So, how does a composting toilet work?

A composting toilet breaks down human waste through aerobic decomposition instead of using water. Liquids and solids are separated into different containers to facilitate faster composting. The end result is a dry, odorless humus substance that can be used as fertilizer.

How Does A Composting Toilet Work EASY Guide

What is a Composting Toilet and How Does it Work?

A composting toilet, also known as a waterless toilet or dry toilet, is a sustainable alternative to a flush toilet. Instead of using water to dispose of waste, composting toilets use natural biological processes to break down human excrement.

The key difference from a traditional toilet is the separation of urine and feces. By keeping the liquids and solids separate, composting toilets significantly reduce odor and make waste disposal easier.

Key Components

Composting toilets have a few key parts:

  • A divider or urine diverter to separate liquids and solids
  • A well-ventilated solids composting chamber
  • Access doors to remove finished compost
  • A liquid collection tank
  • An exhaust vent and fan to manage odors

Dry vs. Wet Composting Toilets

There are two main types of composting toilet systems:

  1. Dry composting toilets: Urine and feces are separated immediately. Liquids drain away while solids fall into a storage container. A fan circulates air to dry out the waste.
  2. Wet composting toilets: Liquids and solids collect together in a chamber below the toilet seat. The waste composts over a long period of time with minimal maintenance.

Dry systems actively manage moisture content for faster composting. Wet systems require less energy but take much longer to break down waste.

For those reasons, dry composting toilets are better choices for full-time residential use.

How to Use a Composting Toilet

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Using a composting toilet is very similar to a traditional toilet:

  1. Add a carbon material like coconut coir or sawdust to the solids container.
  2. Sit down on the toilet seat and do your business.
  3. For proper liquid separation, you must sit when peeing.
  4. Close the toilet lid and allow the waste to compost.

The added material absorbs moisture, prevents odors, and facilitates composting. Fans and heaters built into some units further speed up waste decomposition.

When the solid waste container gets full, the compost can be emptied and used as soil amendment. The liquid tank also needs periodic draining as needed.

Tips for Using a Compost Toilet

Follow these tips to keep your composting toilet operating properly:

  • Sit down to use the toilet for proper waste separation.
  • Try to lean more forward or backwards on the toilet (depending on your needs).
  • Keep ventilation fans running to remove odors and keep it dry.
  • Drain the liquid tank before it gets full.
  • Remove composted waste as needed.
  • Clean all toilet surfaces regularly.
  • Add a solution containing white vinegar if you get any smell from the liquid tank.

Composting Toilet Maintenance

While low-maintenance compared to septic systems, composting toilets do require some routine maintenance:

  • Removing compost: About once a year, remove decomposed waste from the solid storage container. Wear gloves and a mask to avoid contact with partly composted waste.
  • Cleaning the toilet: Sanitize toilet surfaces regularly with natural cleaners to prevent odors and keep the toilet looking clean.
  • Checking components: Ensure that fans, vent pipes, drains, and other parts are functioning properly.
  • Managing moisture: Add bulking material as needed to soak up excess moisture in the solid waste container.

With proper use and maintenance, composting toilets provide years of reliable service. But neglecting minor maintenance issues can cause unpleasant odors and clogged drains.

Choosing the Right Composting Toilet

One of the most popular models in the US is the Nature’s Head self-contained composting toilet:

With different styles and features available, keep these factors in mind when selecting a composting toilet:

Toilet Type

Dry composting toilets with fans offer faster composting for full-time residential use. Wet composting toilets work for cabins or intermittent use.


Calculate the toilet’s needed capacity based on the number of users and frequency of use. Units range from portable 5-gallon models to large composters for whole households.

Power Source

Electric composting toilets require access to power for ventilation fans and heaters. Non-electric units rely solely on natural airflow for ventilation.


Select a toilet style and size that fits with your bathroom’s aesthetics. Some companies offer contemporary styling similar to conventional toilets.

Ease of Installation

Basic units only require securing the toilet base to the floor. More complex systems may need special venting or drainage considerations.

Ease of Use

Opt for a toilet with well-designed seating, liquid diversion, and compost access. Features like composting speed and odor prevention also impact usability.

Advantages of Composting Toilets

Why should you consider installing a composting toilet? Here are some of the main benefits:

  • Water conservation: Composting toilets use little or no water, saving thousands of gallons per year compared to flush toilets.
  • Off-grid use: They allow for toilet facilities without connections to sewer systems, septic tanks, or leach fields.
  • Environmental benefit: Composted human waste can be used as fertilizer rather than polluting groundwater or waterways.
  • Odor reduction: Separating liquids and solids minimizes unpleasant odors.
  • Potential cost savings: Over the long term, composting toilets can save on water and sewer bills.

For these reasons, composting toilets shine in eco-friendly homes, remote cabins, and off-grid installations. They provide reliable sanitation while benefiting the environment.

Disadvantages and Challenges

Composting toilets also come with some downsides to consider:

  • Higher upfront cost: Quality composting toilets cost $1,000 or more. This is significantly more than basic flush toilets.
  • Ongoing maintenance: Although low-maintenance overall, composting toilets require more routine care than flush toilets, because you will need to regularly empty the tank and solid waste container.
  • Space considerations: Many composting toilets require more space than traditional toilets to hold waste containers.
  • Learning curve: Getting the right balance of liquids, solids, and bulking material takes practice.

Composting toilets also aren’t a fit for some densely populated urban areas due to sanitation regulations. Ensure that local codes allow for composting toilet use before purchase.


Here are answers to some common questions about composting toilets:

How much waste can a composting toilet handle?

Capacity depends on the toilet size, number of users, and frequency of use. For a family of 4 using the toilet daily, a medium to large composter (1.5-2 cubic feet) should provide adequate capacity.

Do composting toilets require electricity?

Some composting toilets run on 12V or 110V power to operate fans, heaters, and control panels. Non-electric passive units rely on natural airflow for ventilation.

Where can the compost be used?

In most cases, composted human waste can be safely used to fertilize non-edible ornamental plants, trees, or lawns, if local regulations permit. It should not be applied directly to edible crops.

How much water do composting toilets use?

Dry composting toilets use no water for flushing or moving waste. Some wet units use a small amount of water for flushing, but far less than a regular toilet.

Do composting toilets work for cold climates?

Yes, but composting slows considerably in cold temperatures. Toilets with built-in heaters or that are kept consistently warm work best in cold climates.


In conclusion, composting toilets provide an eco-friendly, water-saving alternative to conventional flush toilets. By separating and decomposing waste, they allow for sustainable waste management without sewer connections.

While requiring more active maintenance, they can be a smart choice for off-grid tiny homes, RVs, boats, and green-built homes. Just take your time to learn proper use and maintenance to keep your composting toilet working effectively!

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