Everything You Need to Know About Composting Toilets But Were Afraid to Ask

by: EJ on 01/23/2019

Ann Baird and Gord Baird's new book Essential Composting Toilets: A Guide to Options, Design, Installation, and Use answers every question you might have ever had about composting toilets  - how to use them, install them, compost the resource and more. 


Gord Baird is our guest today and answers your questions from how to retrofit to what to tell the neighbours.

1) How can I find out if composting toilets are allowed in my region? If they aren’t, what can I do?
There are two routes one can take to investigate the regulations around composting toilets.
1. The first route I would suggest is to inquire with the health agency that has jurisdiction over your area. In Canada this would look like contacting the local Health Authority or Provincial Ministry of Health; in the US it would look like contacting the State Health Agency or the city/county department having jurisdiction over onsite septic and sewer system.
2. The second route is to inquire with the local building official. If they are not explicitly allowed, then you still have a few options. Ask forgiveness (not recommended); ask the authority if there is a route for a variance; or become a dedicated citizen to advocate for change. In any instance it is always really important to have information on your side such as what jurisdictions do allow composting toilets and what standards do exist that speak to composting toilets (e.g WE•Stand, or the BC Manual of Composting Toilets and Greywater Practice). To help you sort through where to look, start at searching those states or provinces that have issues with water scarcity and drought, as it is those jurisdictions that have had to begin looking at alternatives to conventional flush toilets to conserve water.


2) Can I retrofit a composting toilet into an existing bathroom?
The answer is a resounding yes. There are several types of composting toilets that can replace the toilet in your bathroom and require minimal modifications. The most appropriate ones are “batching” toilets, which means that collections are made, and then when the collection receptacle is full, the receptacle is transported outside to a  composting system where the materials are placed and composted. With these “batching” systems, some can incorporate urine collection and urine diversion which keeps
moisture separate from the solids. Other systems collect everything together (and require the addition of carbon materials like wood shavings). One thing they all require is dedicated ventilation of the toilet to allow the toilet to vent outside; it’s the venting that one would consider a modification. Many people install their compost toilet beside their existing flush toilet if space permits. Examples of toilets that fit into this “batching” category are the Humanure Bucket (commode/batch), Nature’s Head, and Separret. There are some systems that are touted as all-in-one where composting/processing occurs in a sealed toilet unit. These systems are called “self–contained continuous” systems. In these, the toilet has a storage compartment that allows materials to degrade and fluids to drain off, and a method to mix and agitate the contents. These are the most common systems sold, highly marketed, but in reviewing them they also tend to have a high variability of user satisfaction. I would also add that the finished materials that are collected from these toilet systems are not safe for use unless further composted. The reason for this is that there is a continual addition of waste (nitrogen and pathogens) that maintain
the pathogens in the finished materials. To address this, the finished materials would need to undergo an additional composting process outside very similar to the “batching” systems noted above.

fig-12-7-ibc-composter (2)

3) How can I be sure that dangerous pathogens are not getting into the environment from my compost pile?
There are two potentially dangerous components in our compost pile that we need to address; pathogens (as pointed out in the question), and also phytotoxins  ammonia/nitrogen). The simple answer to the question is to compost the collected materials long enough so that the pathogens have an opportunity to die and the excess nitrogen is consumed through biological activity in the compost pile. Our book lays out a pathway for each to be addressed. If you have a hot/thermophilic compost pile,
then one could say that the compost is safe when let to age one additional year after the last addition to the compost pile. If you have a cool compost pile (mesophilic) then you may need to let it age for 18-24 months after the last addition. It is really important to realize as well that the compost pile can leach pathogens and phytotoxin/nitrogen into the environment and there are several best practices that should be followed. Compost piles should be situated 100 ft away from wetlands and water sources, should be able to be covered with a roof or lid to shed excess rainfall, and should be built in such a manner that the area directly beneath the compost pile is like an absorptive sponge.


We have moved to creating compost processing piles using recycled IBC 1000L totes with drain ports. The tote’s drain can be plumbed into either a miniature septic field or existing sewer to address contaminated fluid from leaching into the environment. Pictures of this tote system are in the book as well, and the picture is worth 1000 words.
There is also a compost processing method that does not use a compost pile which uses a large wheelie bin like what people use for their curbside garbage pickup. In these systems, compost toilet collections are placed in the wheeled bin and then set to age (moulder) for 18-24 months. These avoid the issues of leaching that is associated with compost piles.

fig-12-7-ibc-composter (3)

4) Should I tell my neighbours I have a composting toilet?
Whatever floats your boat. In all seriousness, if you are installing a composting toilet within the regulations for your area, then there is no need to advertise how you are handling your resources (wastes). I cannot say I have ever had a neighbour tell me they are using a gravity fed septic or pressurized septic system, or a composting toilet system...however this topic may come up if you host a neighbourhood potluck. If you are choosing to fly under the regulations for whatever reason, then there are important best practices to follow that make up the basis for the existing regulations that do exist. The book basically covers these and includes such things as types of composting piles, setbacks to property lines and water sources, managing rodents, and general safe handling. If you are proud of your toilet and want others to know, then by all means, invite them over for enough food and drink and point them to your toilet.

fig-12-7-ibc-composter (4)

5) What model of composting toilet do you prefer?
I used to say that I preferred the humanure bucket system (commode batch), but after writing the book I no longer have a preference. I see all the different types of toilet systems out there serving different needs, filling different niches. I do love the simplicity of the bucket system, but I also would not hesitate in using a mouldering toilet like one of the carousels or wheelie bin systems. I am currently designing a vacuum toilet for a client. I used to hold my nose at the concept of the high-tech toilet systems as initiated by the Reinvent the Toilet Challenge, but have come to realize why and where they make sense over other systems. The book has a decision-making key to help one narrow down what may best suit their needs, and runs through a discussion of the basic concepts of different composting toilet designs to help them choose. I hope that people come to the conclusion that there are many different waterless toilet options that offer safe hygienic resource collection (waste treatment) that fit many different situations and
personal preferences.

6) We have a SunMar electric composting toilet. How important is venting, and can the vent have any bends in it (i.e., up around an eave and back over the roof)? Thanks in advance!

Venting is of huge importance.  Actually for me it is one of the most important aspects that makes the toilet usable. The Sunmar systems are usually sold with their own fan for install.  Bends and horizontal section of piping are not ideal as the allow for condensation which promotes bugs and odors.  There is a diagram in the book that offers several suggestions, including how to utilize existing bathroom ceiling fans.  A picture is worth 1000 words.  (Editor's note: download these diagrams from Essential Composting Toilets  here)


blog comments powered by Disqus