A method and system having a water-flush toilet having a toilet bowl that is in fluid communication with a water source and is mounted with a sensor. The sensor includes a transmitter to transmit an ultrasonic signal and a receiver to receive an ultrasonic signal. The sensor may measure a Time of Flight (ToF) of the signal to obtain a ToF measurement. A microcontroller is electrically connected to the sensor and may receive and process the ToF measurement using an algorithm to determine a bowl status. The toilet also includes at least one water valve that is disposed between the bowl and the water source, and that is electrically connected to the microcontroller for instructing the at least one water valve to move from a first position to a second position for a duration of time, wherein the duration of time corresponds to the bowl status.