Introduction by Steven A. Esrey
Why do people want sanitation today? The most common reason given is for better health. People also want it for convenience, privacy, efficiency, dignity and status among other reasons. We want cars too for transportation. We want convenience, privacy, efficiency, dignity and status as well.
Just like a car and a highway system reflect our culture and values, the toilets and sanitation systems installed around the world also reflect our culture and values. Unfortunately, they reflect a culture of linear flow of resources, waste generation and disposal.
Ecological sanitation is also reflective of a culture and values, albeit an alternative one. It is an alternative philosophy, one with ecological design and systems thinking. Thus, ecological sanitation is more than a toilet or a technology. It is an alternative view of life of how we should live on this planet. It is about restoring communities, protecting cultures, preserving resources, and protecting biodiversity. This is how most of humanity lived until last century.
Ecological sanitation systems are designed on the cyclical principles of natural ecosystems. External inputs into the system, like water, and "wastes" that exit the system, like nutrients, are reduced to a minimum or eliminated. Thus, ecological sanitation systems are designed to render pathogens harmless close to where people excrete them, use no or little water, and recover and recycle nutrients.
By adhering to these principles, ecological sanitation systems help to solve some of society's most pressing problems - infectious disease, environmental degradation, water scarcity and the need to recover and recycle nutrients for plant growth. In doing so, it also helps to restore soil fertility, conserve fresh water and protect marine environments.
Those promoting and ecological sanitation systems take an ecosystems approach to the problem of human excreta. Urine and faeces are considered valuable resources, with distinct qualities, that are needed to restore soil fertility and increase food production. Prior to recycling nutrients, urine and/or faeces may need to be processed. Many of the plant nutrients in urine are readily available to be taken up by plants, while most of the pathogens causing illness are in the faeces. Thus, it makes sense to divert urine from faeces to keep urine relatively sterile, while making it easy to process and treat feaces to render them harmless. Faeces, which contain most of the carbon in excreta, can be rendered harmless by several processes and returned to the land as a soil conditioner as well as returning other valuable nutrients.