Abstract: An alternator valve assembly particularly suited for below ground level use in septic systems for diverting flow from a single inlet to either of two separate outlets. The valve is comprised of a plastic housing which defines a valve chamber having an inlet, a pair of outlets, and valve plug seat means located in the housing adjacent each outlet. A rubber valve plug is adapted to be received in the valve chamber in one of the outlets to selectively block flow therethrough. The plug includes a sealing lip cooperable with the valve seat of the associated outlet and includes an elongated handle protruding outwardly of the valve housing to facilitate movement of the plug between blocking positions with each of the outlets. An outlet box defining a hollow outlet box chamber and having an exit area may be disposed in operative communication with each of the valve housing outlets.