An apparatus and method for measuring a liquid level in a vessel using an acoustic wave. Acoustic tubes have first ends disposed vertically along a sidewall of the vessel for each of the liquid levels to be measured, and the tubes communicate with the inside of the vessel. Second ends of the tubes are connected to a common tube. A storage level sensor board generates the acoustic wave in the vessel, receives the acoustic wave propagated through the acoustic tubes and the common tube, and determines the level of liquid in the vessel based on the received acoustic wave.