'It's a Big World, Everyone Shits, and Everyone Needs a Toilet'

What is a compost toilet and how does it relate to Africa? That was the focus of my month-long trek through Tanzania, Uganda, and Kenya in March 2018. Since I'm considered a compost toilet "expert," my job was to spread the word about composting as a sanitation solution, introduce people to compost toilets, design and build compost toilets and compost bins, conduct impromptu trainings and seminars, and monitor and document compost toilets installed in schools, villages, prisons, game parks, and households in slums, cities, and in remote locations. I learned a lot!

It helped that Cape Town was facing a "day zero," or a day when the taps run dry and toilets no longer flush. There was a lot of chatter online from South Africans trying to come up with alternatives to the flush toilets they so depended upon. There is obviously a lot of misinformation and confusion surrounding this topic. For example, there's a big difference between "compost toilets," "composting toilets," and "dry toilets." A dry toilet is any toilet that doesn't depend on water to function, like a flush toilet does. This can include things like incinerating toilets and chemical toilets, for example, as well as a compost toilet, which is a type of dry toilet.

A "composting toilet" is kind of like a unicorn, it doesn't really exist, but people keep repeating the term anyway. Composting doesn't take place inside toilets, hence the term "composting toilet" is not only incorrect and misleading, but it damages the composting industry, because "compost" and "composting" are real things with specific requirements and characteristics.

What people refer to as "composting" toilets are actually dry toilets designed to dehydrate the toilet contents. You can call them waterless toilets, or biological toilets, or ecological toilets, but don't call them "composting" toilets. The toilet contents are dehydrated by draining or diverting urine, by venting out moisture, and by heating the toilet contents using external heat sources such as electricity or solar. These toilets often use a carbon-based cover material, like compost toilets do, and the dehydrated organic material may eventually look something like compost, but it isn't. (1)

Most dry toilets do not compost because the toilet contents don't generate internal biological heat, primarily because of their small organic masses and organic material that is too dry. When organic material is subjected to a true composting environment, it is converted into humus or soil by microorganisms while human pathogens are eliminated or significantly reduced. Dehydration toilets do not achieve composting, although their contents can later be added to a true composting system and presumably thereby processed for pathogen removal.