In the Eastern Region of Mekong Delta (South Vietnam) may contain brackishor saline water from land surface to great depth, both superficial Quaternary and deepTertiary Alluvium. The combination of two geophysical methods, the Vertical ElectricalSounding (VES) for shallow investigation, and the Magnetotelluric Sounding (MTS) fordeep investigation, provides a complete electrical image of the sedimentary series from thesurface to the deep crystalline basement. It turns out very efficient to delineate thegroundwater contamination in both superficial and deep aquifers. The combined resultsreveal a close correlation of the extent of the contamination with the paleogeomorphologyof laterites, and subsequently with the paleorelief during the Tertiary and Quaternary times.Because this study area is very complicated hydrogeological structure, it is necessary tosurvey the current status of deep-water storage floors with geophysical measurementtechnologies to prevent groundwater pollution when exploiting groundwater here.