Ground water plays an important role for civil works and underground environment. The latest model ground water flow meter is tested in laboratory to verify its applicability for Vietnam-made PVC pipes which have different slit shape and interval from Japanese pipes. The test result shows that the GWF Meter works propoerly even in Vietnam-made PVC pipe. Filed application in Japan shows that the GWF Meter is useful to solve water leakage problem of ponds or lakes resultinfg preservation of a historically siginificant emvironment.