More than 28 million households have septic systems, but few homeowners know how they operate or how to maintain them. This clearly written, illustrated guide addresses that need, emphasizing conventional septic systems powered by gravity flow, filtering through soil, and the natural soil organisms that purify sewage. The book discusses maintenance, what to do if things go wrong, and alternative systems such as mounds and sand filters. Additional chapters cover graywater systems, composting toilets, and a unique history of water-borne waste disposal. This expanded edition contains three new chapters.