Compost Toilets: Turning Human Manure Into Essential Resources

Using a compost toilet in place of a flush-toilet reduces the addition of unnecessary chemicals to the environment from the conventional treatment process.  Compost toilets also reduce the need to use valuable drinking water to flush excrement, and require no energy to operate.  In addition, the human manure becomes benign compost that can then be returned to the soil, increasing soil fertility and reclaiming valuable nutrients.

Through natural biological processes, composting toilets turn human manure into benign humus that can be added to the garden.  Aerobic microbes oxidize the organic material creating carbon dioxide, and hydrogen atoms are converted to water vapor.[1]  This process closes the human nutrient cycle, a practice that is fundamental to sustainable agriculture.[2]  There are many different types of composting toilets available commercially however, composting toilets could be made by any homeowner for a fraction of the cost, and we have seen hundreds of beautiful designs built in homes, attached to homes, and in backyards. 

There are two types of composting systems—those that are “cold” (mesophilic) which comprise the majority of composting systems, and those that are “hot” (thermophilic).  Hot systems depend on more involved attention and involvement, because the contents of the toilet must regularly be emptied into a compost pile where it can mature.  Cold systems require little maintenance, with most designs requiring emptying only once a year.  In fact, systems can be designed so that they don’t have to emptied for decades if the storage volume is three times the annual capacity requirement.[3]  Cold composting toilets create organic material that is a fraction of the original poop volume and is safe to handle as the year-long settling time cures most pathogens. While raw humanure can carry disease pathogens, the process of composting destroys them – in fact, most are killed in a matter of minutes in a thermophilic (hot) compost.[4]

Compost bins: turning organic waste into essential resources

Most of the trash thrown away in the world is organic matter that will naturally decompose if left in the open air, and will turn into nutrient rich material for the garden if it is mixed with enough dry “brown” carbon-containing matter such as: dry leaves, dead plants, straw, shredded paper, sawdust (from untreated wood), pine needles, etc.  It is one of the easiest ways that everyone can participate in reducing the volume of garbage generated each year, while simultaneously regenerating the soil.  It is as easy as creating a designated place in your garden to throw all of your kitchen scraps and yard waste. 

When larger collections of waste are required, the three-bin system is a simple solution to compost all organic waste created on site.  This system involves two bins for waste and a third, covered, bin for storing dry material that will be added to the green matter.  The multiple bins allows for easy filling of one side while the other side matures.

We coordinate with communities in need for each of our offsite workshops on composting, culminating with an installation project of a three bin composting system and/or a composting toilet in the community. Workshops will include education on the environmental degradation caused by conventional black water treatment systems and the advantage of composting human manure on site. We will also cover maintenance, and system design considerations with special emphasis on the system that workshop participants will install.