What is the purpose of a cleanout in plumbing?

A cleanout in plumbing serves the essential purpose of providing access to the drainage system for cleaning and maintenance. This access point is critical because it allows plumbers to remove blockages, perform inspections, and ensure the proper functioning of the drainage system. Cleanouts are strategically placed at key points in the plumbing system, such as changes in direction or at regular intervals, to enable effective cleaning without the need to dismantle extensive sections of piping.

While one might think about the other options, they don't specifically define the role of a cleanout. Venting is addressed through vents, waste disposal is the main function of the drainage system itself, and connecting different sized pipes pertains to fitting and transitional pieces in plumbing but does not relate to cleanouts. Thus, the function of a cleanout is fundamentally about maintenance and efficiency in plumbing systems.