A system for managing liquid supply is provided. The system includes an air pressure adjustor, a first liquid container, a second liquid container, a first tube, a second tube, an inlet sensor, and an outlet sensor. The first liquid container includes a liquid. The second liquid container includes an inlet and an outlet. The first tube is configured to be connected between the first liquid container and the inlet. The second tube is configured to be connected between the outlet and the air pressure adjustor. The inlet sensor is disposed on the first tube and for detecting the liquid flowing into the inlet. The outlet sensor is disposed on the second tube and for detecting the liquid flowing out from the outlet.