Most soil treatment systems depend on gravity to distribute wastewater out into lateral trenches. Using gravity alone, however, means some areas of the trenches receive very little wastewater while other areas are overloaded. Low-pressure piping (LPP) systems evenly distribute wastewater over the entire soil treatment areas. The discussions on design and construction are intended to enable engineers, soil scientists, sanitarians, and installers to design, construct, and inspect low-pressure piping distribution systems. ©2022.