A cleanout port drain assembly providing a P-trap for a drain system. The cleanout port drain assembly having an upwardly extending, front facing cleanout port section with a detachable end cap. Removal of the end cap exposes an opening into the cleanout port section. A nozzle of a suction device or a snake may be inserted through the opening and into the cleanout port section to cause a clog to be dislodged and pulled from the drain system out through the opening in the cleanout port section to enable the drain system to drain.