Collection components of residential systems are generally limited to a solid, rigid pipe collecting wastewater from plumbing fixtures and appliances. This pipe, laid on a 1-2 percent downward slope (¼ in per ft), exits the structure, and extends to the pretreatment component.
A clean-out should be located in the pipe before the first pretreatment component. Depending on sampling needs and requirements, adequate sampling basins should be located between components.
Some sites may have elaborate alternative collection systems. These systems may have pump tanks collecting the waste and subsequent transmission lines for transporting it to the pretreatment components. Holding tanks can be considered storage devices, because they essentially store wastewater until it is collected and transported to a different site for treatment and dispersal.