All living systems must continuously process materials for building and maintenance of their bodies. To do this they must have inputs of energy through food and water and must get rid of materials through respiration and excretement. Humans, through the manufacture and use of goods, create additional materials that are used and discarded. Collectively, the things we think we don't need have been termed wastes. Waste collection, processing and treatment systems must be part of every design.

Permaculture design is based on the premise of minimizing wastes. What is often labeled as "waste" by society is indeed a resource for us. The usual materials coming off a site are "hard" construction and rock, "soft" plant organic matter, "household" paper, plastics and cardboard and "human" grey and black water.

The easiest to deal with is the "soft" organic plant material. It gets composted, placed in worm boxes, fed to animals, used for mulch, or otherwise placed back in the nutrient and soil building cycle. In most developed world communities this resource is lost to garbage disposal units and leaf bagging, becoming a problem rather than a solution. Meat, the other household organic waste, can be fed to animals; bone may be dried and pulverized before composting.

The "hard" construction and rock materials are usually not a problem as they are infrequently generated and much of it can be used on site to make paved areas, subsurface drains and water retention pits. The rock walls of New England provide an excellent example of "waste" conversion to productive function. Wood waste can be chipped and composted or burned for the ash. I have a sturdy path constructed of the asphalt shingles from an old roof.

"Household" materials are being more and more directed to community recycling schemes. The first line of defense is to try to stop generating it, a difficult task to do if one's name is on mailing lists or if one must buy items in the normal consumer market. However, one may purchase with attention to recycling and some materials may be reused on site. For example, newspapers, cardboard and such paper products may be incorporated into garden walkways or sheet mulch where they eventually decompose to become part of the soil.

The most difficult wastes are personal grey and black water mostly because of the potential for carrying disease agents. Greywater, water from showers or washing of clothes or dishes, can be used on non-consumable herbaceous plants, berries, and orchards with impunity. Black water, sewage, causes more difficulty.

Common sewage treatments have included surface disposal and direct fertilization, a disease vector; outhouses and pits of various scales, a potential ground water problem but a usable approach; feeding of animals or fish, a problem of producing parasites; septic fields, appropriate for small dispersed installations; into the water after treatment, the typical urban solution causing nutrification of receiving water bodies; and incineration, a high user of energy creating ash as waste. Less common systems include biodigestion, where sewage is turned into energy and fertilizer; composting toilets, where the end product is a usable compost; wetland treatment; with the benefit of biological purification and use of nutrients prior to effluent release; and living machines; where the process ends in pure water in a relatively small treatment area because of intense biological activity.

The extent and type of system for treatment of human waste is largely dependent upon the number of people and the nature of the receiving environment. The trend is to develop systems that use human waste as a resource and try to render in pathogenically harmless while using its nutrient content. On a large scale, the most promising systems seem to be wetland treatment and living machines, both of which deliver higher quality of water at the end than other systems. At the end of the cycle the water should go onto land systems like forests rather than into water bodies.

For more information on wetland treatment and living machines see: Todd, Nancy Jack and John Todd: From Eco-Cities to Living Machines.