Automatic bathtub overflow drain switch

A bathtub overflow shutoff system comprising:

• a bathtub having a bathtub wall, a hot water supply line, and a cold water supply line, the bathtub wall defining an overflow drain opening positioned at a predetermined water level below a rim of the bathtub;
• an overflow drainpipe connected to the overflow drain opening and extending downward from the bathtub wall;
• a tee pipe connector coupled in-line to the overflow drainpipe at a position below the overflow drain opening, the tee pipe connector comprising a flow path that receives water descending through the overflow drainpipe and a lateral sensor port extending transversely to the flow path;
• a flow switch assembly comprising:
• a flow switch sensor received within the lateral sensor port of the tee pipe connector and positioned to contact water flowing through the tee pipe connector,
• and
• a flow switch housing enclosing switching circuitry electrically connected to the flow switch sensor;
• a controller communicatively coupled to the flow switch housing, the controller comprising logic configured to transmit a valve-close command in response to a signal received from the flow switch assembly;
• a first solenoid valve installed in the hot water supply line upstream of the bathtub, the first solenoid valve transitioning from an open state to a closed state upon receiving the valve-close command;
• and
• a second solenoid valve installed in the cold water supply line upstream of the bathtub, the second solenoid valve transitioning from an open state to a closed state upon receiving the valve-close command;
• wherein, when water in the bathtub rises to the overflow drain opening and flows downward through the overflow drainpipe and through the tee pipe connector, the flow switch sensor detects the water flow and causes the flow switch assembly to signal the controller to simultaneously close the first solenoid valve and the second solenoid valve, thereby terminating water supply to the bathtub.