quid waste disposal system, to identify any potential problems, and to select and design a system that will provide adequate protec- tion at minimal cost. Further, because a very large percentage of failures of systems designed to overcome particular site limitations are due to faults in construction and installation, step-by-step proce- dures are presented, along with common mistakes to be avoided. Finally, proper maintenance procedures are described SO that the system will perform as designed for many decades. PART I An Overview of Onsite Wastewater Disposal Regulations and Processes CODES AND REGULATIONS It is an unfortunate fact of life that bureaucracy lags behind tech- nology. In general, committee-prepared codes such as the Uniform Plumbing Code (UPC) and state regulations inadequately address on- site liquid waste disposal systems. Alternative kinds of liquid waste disposal systems are often not addressed at all. Only recently has the U.S. Environmental Protection Agency (EPA) come to recognize that onsite systems can be more than a temporary alternative to municipal treatment plants. As a result of this bureaucratic inertia, many areas of the country are limited in the types of onsite systems that can be installed. Misinformation has prejudiced homeowners, contractors, and enforcement officials against particular alternative systems. On the other hand, some areas have adopted a particular alternative with open arms, only to find that unforeseen problems made the alterna- tive unworkable. Most states have reasonable environmental health protection requirements such as system to ground water clearances and setback distances to wells. What is considered reasonable varies from state to state. For example, according to the published pro- ceedings of an EPA conference on onsite wastewater disposal, the required distance from the bottom of a leach field to the ground water table varies from no minimum to 4 ft. According to the National Environmental Health Association, some local codes require up to 10 ft of se