A cleanout is a component in plumbing that allows the plumber or someone accessing pipes to clear out any kind of blockage of debris which has accumulated in certain parts of the system.
A cleanout is routinely placed at a connection point in sewer lines. A cleanout will be located at the bottom of a vertical stack, where it meets a horizontal sewage line. A cleanout is placed at the most likely place for debris to collect and block the line.
Parts of a Cleanout
All a cleanout is, basically, is a large plug that is able to be unscrewed, in order to access an opening in a pipe where blockages tend to occur. The parts of a cleanout are simply the female thread adapter on the cleanout section of the pipe, and the male threaded cleanout cap.
Sometimes access to a cleanout is placed within a wall, and in that case, the male cap of the cleanout should be located as close to the wall as possible, to give the easiest access to a plumber.