Abstract: The present invention refers to an apparatus for measuring the level and/or volume of a liquid stored in a container. The apparatus comprises at least one pair of electrodes mounted in the interior of the container in such a position that said electrodes are partially or totally immersed in the liquid stored in the container, said pair of electrodes acting as one of the capacitors of a Wien bridge to modify the output signal generated by the bridge-circuit to, in addition to measuring and indicating the volume of the liquid, also providing an indication of the quality of the liquid in the container and/or the ratio between two different types of liquid stored in the container.