One area chosen for the application of DEWATS is the private household of Mr. Hau, in Huu Hoa Commune, Ha Noi City, Viet Nam. As one of the thousands of households in Viet Nam using only a simple, bottomless septic tank that had never been desludged, the house was not eff ectively treating its wastewater. Groundwater pollution is being experienced resulting from the leaching of wastewater from the septic tank. While the single house generates only a small environmental and health risk from its pollution, when this issue is compounded across thousands of similar households in Viet Nam (and elsewhere in Asia), this small problem becomes a major issue. In fact, improperly maintained or constructed septic tanks are one of the biggest issues currently facing the urban sanitation situation of Asian cities.