ntenance required on holding tanks is the reason everyone doesn't use them. An average household of four persons would fill up a 1000-gal holding tank in five days. At only $50 per trip, the pumping bill would be $3650 annually. Because of the high maintenance cost, it is wise to reduce the volume of flow entering a holding tank as much as possible. A composting toilet could cut water use by more than half. Low-flow fixtures throughout the ONSITE WASTEWATER DISPOSAL house could help. The section on water conservation gives tips on methods to reduce water use. As an example, an air-assisted one- quart flush toilet combined with other water-saving practices could cut the annual maintenance cost to less than $1000. COMPOSTING TOILETS Application For much of the history of human civilization, human excrement has been recycled as fertilizer. When large numbers of people became concentrated in small areas (cities), problems with excre- ment collection and removal and the associated odors made life unpleasant at times. So from time to time water carriage sewage systems were developed and used to get rid of this sometimes nox- ious material. After it was discovered that there was a direct rela- tionship between contact with human excrement and disease, water carriage sewage systems were considered an imperative for a civi- lized society. Only recently have some people been asking how smart it is to take a precious natural resource, defecate in it, and then send it out into the environment to contaminate more of that same resource. To many of these people, a compost toilet represents the only sane way to handle treatment of bodily wastes. Compost toilets require no water for operation. They isolate and eliminate most pathogenic organisms, and provide a useful by- product. However, they also require considerable attention to work properly, may not be approved for use by local authorities, and can also be expensive. In addition, compost toilets do not accept "grey water" (household wastewater not coming from a toilet), SO i