A bathtub system, including a tub with a bather access opening in one sidewall and a door mounted on that sidewall. In the closed position, the door is adjacent the access opening, and in the open position the door is substantially clear of the access opening. The system includes a gray water reservoir under the tub of approximately the capacity of the tub and which can be connected to a sewer system. A high capacity toroidal tub drain conducts water from the tub into the reservoir by gravity alone very quickly.