Abstract: Apparatus and method for obtaining from a well drilled into the subsurface of the earth the information necessary to determine the location of the liquid surface in same. A source of pressure pulses is coupled to the well surface casing in order that the pulses are transmitted downhole where they are reflected by all surfaces present therein such as, the liquid surface, tubing collars and tubing anchors. A transient pressure transducer is provided which generates an electrical output in response to all reflections of the transmitted pulse. All of the reflections occurring in the well are recorded for a sufficient amount of time to ensure the recording of the first reflection from the liquid surface present in the well.