A three phase separator to separate a fluid into three phases. A horizontal tank forms a fluid container having an inlet to the container in order to permit entry of a three phase fluid. An oil box within the fluid container includes a bottom and at least one baffle separating the oil box from the fluid container. A water box within the fluid container includes a bottom and at least one baffle separating the water box from the container. A water removal mechanism is in communication with the water box to draw water therefrom. An oil removal mechanism is in communication with the oil box to draw oil therefrom. A gas outlet permits removal of gas from the fluid container. A slot through the baffle of the water box permits entry of water from the fluid container into the water box in the event of a water surge.