Abstract: A directional potential analyzer method and apparatus using a non-intrusive electrical measurement technique to obtain a precise location of a leak in a geomembrane liner. The method and apparatus can be used for detecting leaks in either a single layer or a two layer geomembrane liner. The directional potential analyzer comprises a differential voltage detection probe which is moved through the liquid with the potential difference between the electrodes on the probe being measured and recorded as a function of azimuthal position of the probe. An initial scan of the liquid impoundment is used as a reference trace showing all of the anomalies of an unfaulted liner. Subsequent traces obtained by rotating the analyzer probe at a later date are processed and compared with the reference trace to determine the occurrence of new anomalies representing leaks in the liner.