To avoid the logistics of flooding the geomembrane with water, the exposed geomembrane can be tested for leaks using a water puddle test. This test is used on geomembranes that are in direct contact with the supporting sub-grade or a GCL. Procedures for this method are specified in ASTM standard D-7002.
 

The bare liner test is to detect electrical current flowing through a hole in the geomembrane liner using a small amount of water that is temporarily placed in contact with the liner using a squeegee.  One output of an LLSI power supply is connected to earth ground or the GCL and the second output is connected to the scanning sensor through an LLSI electronic leak detection unit.  When the water in the leak contacts earth ground or the GCL, a circuit is established and the electrical current will increase. The LLSI electronic leak detector unit converts the increase in the current to an audible tone indicating the presence of leak.