Design 9- Composting Toilet

Design of a composting toilet system for one of the four apartments on my site. It will help me decrease water use and cost, help us in days of high rains when our septic system overflows and also plug one of the main energy leaks on our site which is the ability to use our own humanure as a resource.


This Survey uses the data from the Client Interview and the Overall Site Survey.

Current Arrangement: There is a regular flush toilet in the apartment where this design will be implemented. This apartment is and will be occupied by me for a few years until I rebuild my tiny-house. This current flushing toilet goes into a concrete septic tank on the site which is almost permanently full due to our frequent rains.

When there is more than normal rain, the septic system overflows and can no longer receive water and our toilet either stops flushing or it breaks the seal and starts leaking to my floor. There is one more toilet on the same pipe line which is affected if we flush under these conditions and it is for one of my rental apartments which adds to the urgency of this design.

Below is a diagram of the whole site for orientation:

Below is a diagram of the affected bathrooms and septic line. The first bathroom (North) is the one I use and the one in which I’m implementing this design:

The overall analysis that I have been using for all my site designs, does not take into consideration the issue of septic overflowing therefore it will be added as one of our Needs for this design:

  • Mitigate the problems caused by having our septic tank overflowing by ensuring that there is a waterless toilet available at every moment.

The overall analysis does cover the following Needs related to a composting toilet as seen below:

  • Our desire to lower water cost and waste

  • Increasing local resources like mulch and fertilizer.

  • Completing ten designs for my Permaculture diploma

  • Increasing soil fertility

  • Generating 0 waste

For this design, I will not be covering one of the Needs and Wants:

  • Engender interest in Permaculture and regenerative living- This first system will serve as a test and will be placed in my private apartment. If successful, I will replicate this system in our rental apartments.

Limiting Factors: One of the main concerns is having a system inside the apartment which may release odors and attract animals. There is a significant amount of insects in our site because we are next to a forest and I fear that this system would attract them into my apartment.

Resources: This project’s budget will be adjusted depending on which type of composting toilet I choose. All the building resources on site like tools, wood and nails, the budget are already on site. The building of the toilet would be done by me.

Budget: A budget of $500 will be set aside for this project which will be adjusted after the Analysis and Design phase.

Timescale: 5 days - Either if I buy a ready made composting toilet or if I use the simple bucket system, they both would take me around 3 days to build or install and allow for 2 days to optimize the system.


Key Functions: The most efficient system would be one that uses and recycles all the resources generated on site (Principle 6: Produce no waste). A resource that is not used becomes a loss and a resource that accumulates unused can become a source of pollution (Principle 2: Catch and store energy). Below is a list of the key functions expected from this design based on the client interview and site analysis.

  • Plug one of our energy leaks- By using our current septic system we are losing a resource that could be used as fertilizer (humanure). A simple composting system would help us keep these energies on site to be used on our plants.

  • Mitigating potential threats- One of the main problems in our site is the clogging of our toilets when there is a high level of rain. Rains have become more frequent and stronger over the years and this has caused more problems with the septic system (Principle 12: Creatively use and respond to change). This is particularly problematic for our rental business because one of our rental apartments is connected to the most vulnerable line which is the same one my toilet is connected to. When there is high rain, my use of the toilet makes matters worse for our clients. There have also been times when the water pressure of the backed water is so high that it breaks the seal and it leaks under the toilet, both on my and the rental apartment.

  • Decrease pollution: The current septic system created a polluted anaerobic environment that seeps into the groundwater creating potential environmental damages (Principle 6: Produce no waste).

Ethics- Guidelines within which this design should be completed

  • Earth Care- Without a composting toilet, we are losing a major source of fertilizer. Instead, we flush our toilets after every single use which not only wastes thousands of gallons of water every year but also increases contamination. Our toilets go into a septic system where it combines with water and feces. This seeps into the ground in an anaerobic state and could reach our local waterways. We could avoid this damage with a Composting Toilet. It would also help transform toilet paper into healthy soil turning what is a source of pollution with the current system, into a resource.

  • People Care- This system would generate savings in water and fertilizer which could be used to feed our trees and generate more nutritious food.

  • Fair Share- An increase in the health of our trees would generate additional food which could be shared with the local fauna, guests and family.

Options and Decisions: After using the internet to research the different composting toilet options and their pros and cons, I narrowed my options down to three options as seen below. All three would help us achieve our emergency needs (Septic tank overflowing) but they would all also help us plug these energy leaks, including the use of toilet paper as one of the resources to be composted.

  • Simple bucket: This is the simplest option and it only uses a bucket, e.g, 5 Gallon Buckets, which can be found on most hardware stores. Both solids and liquids mix in the bucket. Everytime this system is used, you would add Coco Coir or Peat Moss or any other composting material to start the composting process and neutralize odors.

    • Problems with this system:

      • The mix would be too humid creating an anaerobic environment. If the bucket is not emptied frequently it may turn into sludge which would increase odors and be hard to clean.

      • The setup in our bathroom does not allow to channel the urine out of the bucket since all the old pipes need to be sealed to avoid leaks from the septic system.

      • There is no way to place an exhaust system in the bathroom without breaking through the roof, something that we don't want to do.

  • Bucket with an urine separator: This system is almost identical to the option above but there is a separate jug that holds the urine. This system uses a diverter seat which connects the front part to the jug using a pipe. Since there is a separation of liquids, there may be no need for an odor exhaust system.

    • Problems with this system:

      • No complaints were found about this system. The only inconvenience would be cost when compared to the first system above. The diverter seat costs around $200

  • Nature’s Head: This is a ready made system that separates liquids and solids and is regarded as very convenient according to the reviews I found. This system is almost identical to the one above plus it has a crank that turns the material while it composts.

    • Problems with this system:

      • No complaints were found about this system. The only inconvenience would be cost when compared to the system above. This system costs around $1300.

      • Some users complain that it is a bit difficult to clean since the solids recipient is part of the unit and it does not have handles to carry it to your compost bin.

Choice of cover material- Cover material is used to cover our humanure after each use. This material needs to be absorbent so it keeps moisture low, good at controlling odors, cheap, porous enough so it allows oxygen and has to be regenerative and ethically sourced.

  • Peat Moss- This material is popular among composting toilet users because it is good at removing odours and moisture but is not sustainable. It is harvested from the bottom of bogs after all the water has been removed. These bogs serve as habitat for living organisms but they are destroyed during the harvest process.

  • Coco Coir- Has to be purchased and cannot be processed on site. It is expensive for daily use. It requires preparation since it comes in dehydrated blocks which need to be soaked in water. This product usually comes from Asia so it has a high carbon footprint.

  • Wood Chips and leafy material- Wood shavings is a cheap option that is readily available in our area. It is good at absorbing moisture and controlling odours. This material will be ideal after I buy a wood chipper with which I will be able to use the material generated on site from our own trees.


Due to cost issues, I chose the second option, Bucket with a urine separator. If successful, it would be cost permissive to buy four more separators for all my apartments if this system is successful.

The diagram below shows a simple system made out of a wooden box with a hole on top to place the urine separator. Under the separator, inside the box and hidden from view, we would place a 5 gallon bucket which will hold the excrement, composting material and toilet paper. A separate jug would be placed next to the bucket to hold the urine. The urine jug will be connected to the separator using a small hose.

The wooden box would be opened by lifting the top portion lid. This lid would be held to the back with hinges and would lift along with the separator in place. This would give us access to the bucket and jug for cleanup and maintenance.

After my research for this design, I chose to use the Kildwick Klassik urine separator. This product can be found on Ebay for less than $180 which falls within our budget, this is especially beneficial since the assigned budget would cover the toilet for the rental apartment if this design is successful. Below is a photo and diagram of the product taken from:

Composting material:

The cover material was chosen based on price and carbon footprint. All 3 options appeared to have similar odour control and absorbency but the wood chips / leaf material are more readily available and cheap. I will experiment with cover material mixes using dry grass clippings and/or compost from our compost pile to see which combination works best (Principle 5: Use & value renewable resources & services). This local option helps us create a connection between our food forest (as recipient and source) and our compost system (as a source of compost element) (Principle 8: Integrate rather than segregate).


This design should be implemented around the start of 2022. There is no specific timeframe but below is an estimate of the progress that should be made in the 5 days I set for implementation.

  1. Day 1: Removal of current toilet, cleanup of the area and sealing of the current pipe. Start building the frame and attaching it to the floor.

  2. Day 2: The frame building using 2x2 and plywood available on site. Nails and hinges are also available.

  3. Day 3: Preparation of the lid adjusting it for the Usine Separator seat and toilet seat. Placement of the bucket and jug. Adding composting material.

  4. Day 4: Test and adjustments

  5. Day 5: Test and adjustments


Maintenance of this system involves the following steps:

  1. Keep an eye on the levels of urine in the jar:

    1. The urine will be disposed into the compost bin to keep the moisture on the material. This will add nutrition to the compost compared to just water.

    2. Flush the urine side of the separator seat by spraying with a 25/50 to 50/50 mix of vinegar and water to clean and neutralize odors.

    3. Rinse the urine jug at least every two weeks with water and vinegar.

  2. Feces bucket:

    1. Keep an eye on the level in the bucket and empty it when it is around half full or less.

    2. Rinse the bucket at least every week with water and vinegar.

    3. Avoid having any liquids fall in the bucket. The material should be dry so it is Aerobic ( An environment in which organisms that grow in an oxygenated environment can survive.)

    4. Always cover after every use with a scoop of wood chips or any chosen material to start the composting process and decrease or eliminate odors.

    5. Wipe and flush the feces side of the separator by spraying with a 25/50 to 50/50 mix of vinegar and water to clean and neutralize odors.

    6. Empty bucket contents into a 50 gallon bin. Once this bin is full, it will be closed and allowed to compost for at least 9 months.

    7. If the toilet paper is eco friendly, it can be thrown into the bucket.


Even though the implementation program states that I should implement this design by early 2022, it may be postponed depending on any upcoming deployments.

At the time of evaluation, we will be looking for answers to the following questions which will be posted in this page and any resulting tweaks would be included here also.

  1. Was there any noticeable increase of insects attracted to the system?

  2. Was there any increase of noticeable smells?

  3. Were there any spills from the system?

  4. Any notes of disposal of the material and its composting progress.


After the evaluation process is completed, after implementation and use, any tweaks performed will be posted here.

Design Process


Learning Pathway Reflections:

It brings me a lot of peace knowing that through Permaculture, I can decide upon an appropriate and ethical technology to solve the problem of my overflowing septic system which has caused me so much stress for decades. On top of this, being able to plug an additional resource loss and integrating this design with my Food Forest and Composting system gives me more confidence to continue searching for connections in my site and in any future projects

How this design helps me apply permaculture in my life:

Even though this system will be implemented in the near future, I’m certain that it will be successful if I follow the recommended instructions on the use of a composting toilet and its maintenance. The use of a composting toilet has amazing benefits, especially if I ever move to a new site because it would provide immense savings by not having to install septic systems or septic pipes. The fact that I can move into a new place and implement regenerative practices which not only offer immense savings but also lowers my negative impact on the planet, gives me a lot of relief.

How this design helps me apply permaculture in my works and projects:

After I tested this design, if successful, I would install it in one of my apartments. After I learn how my guests feel about it, if positive, I would make it a part of my recommendations and services if I ever do Permaculture consultancy.

Principle 12: Creatively use and respond to change

“Vision is not seeing things as they are but as they will be”
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