Rain Wather is dassified an either percolated water when it infiltrates into the ground or runoff water when it flows on the ground surface. Percolated water affects the soil water content and may even modify the soil geomechanic properties to the point of generating instabilities. Runoff water produces a very important laminar erosion. It may as well iniciate surficial ground mass movements, river overflows and flooding.This paper summarizes the results of research work carried out to investigate the water percolation process in different soil types. For the work rain intensity and length were varies.In order to simulate rains, a device 40 cm in diameter and 60 cm high, and disks were designed and constructed. This device was named rain simulator. The work included a close water circuit. A geolectric method named C.E.T.V was designed to investigate the infiltration regime at initial time, (previous to rain), at the time to become swampy (time required for runoff to start) and at several periods of time after the rain had ended.Several aspects of the percolation process such as the depth of the water front at the time to become swampy, crossff effect due to dragging of small particles or to impervious layers, soil cracking, influence of ground slope on depth of infiltration and other aspects were investigated because the C.E.T.V. method allowed readings at several depths, which make possible the preparation of curves depth vs absolute resistivity.