Background: All plumbing codes in general use in the United States include a section of definitions. Among these definitions are the terms "building sewers" and "building drains." Their definitions are uniform except for one detail: the point of transition from the "drain" to the "sewer" is either 2-, 3-, or 5-feet outside the wall. Except for this detail, the code definitions for building sewers and building drains agree. Sewer mains are normally in the public right of way, are part of the public sewer system, and are not usually covered by the plumbing codes.

In addition to defining these terms, the plumbing codes include some requirements for installing buried pipe line. Although these provisions in the plumbing codes have variations in wording and format, they are, as a whole, very similar. They are also very basic and apply to all building drains and sewer pipes, independent of the material.

Their adequacy is evident because the existing plumbing code provisions have been used for many years The installation requirements for buried pipes are identified in most plumbing codes as Trenching, Excavation and Backfill and are located in the general regulations or in an appendix.

Installation of Plastic Building Drains and Building Sewers: PPFA recommends that installers follow the plumbing code provisions for the installation of buried plastic building sewers and building drains except where the code may otherwise provide. The installation and inspection of sewers designed by an engineer because of unusual conditions are his or her responsibility. Questions concerning the use of plastic pipe in building sewers or sewer mains should be addressed to the pipe manufacturer or PPFA.

Installation of Plastic Sewer Mains: Engineers may wish to consult ASTM D2321 as they prepare plans and develop installation specifications for sewer mains. ASTM D2321 -- Standard Practice for Underground Installation of Thermoplastic Pipe for Sewers and Other Gravity Flow Applications -- provides extensive details concerning soil classes and underground soil conditions and how they relate to plastic sewer pipe performance.

NOTE:
This PPFA User Bulletin is designed to provide guidance in achieving the efficient, effective and proper use of plastic pipe. The suggestions and advice contained in the Bulletin are offered merely to provide plastic pipe users with a general frame of reference. Because specific situations may and often do require special treatment, the suggestions and advice are obviously not universally applicable. Therefore, the user should carefully assess the requirements of his specific situation before making practical application of anything contained in this publication.