The selection of aquifers based on Geoelectric Method data in constructing drilling wells was discussed in the present study. The research was conducted at the International Hospital Project in Nyitdah Tabanan Bali. The research position was around 8,5736 LS 115,1215 LE. Before the study was conducted, a well drill (well 1) has been made. The results showed that there were two types of aquifers, namely unconfined aquifers and unconfined aquifers. Related to this study, well 1 took water in the

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... nconfined aquifers of 4 m depth. If the water kept taken for a long period, the quality and quantity of the water would be worse since well 1 was unconfined aquifers that took surface water. This would adversely affect the hospital building being built. The land around the building would be hollow due to the water loss, and the building would become unstable. Another drill well (well 2), based on geoelectricity data, can be made on 5,25 m -18,75 m. In-depth 23 m, it was suspected that unconfined aquifers would have been found in well 2. After being drilled, aquifers were found in 23 m depth. Drilling was kept doing to 55 m depth. The new well (well 1) had TDS 205 mg/l and well 1 had TDS 350 mm/g. The number was still under the recommendation of Health Minister Regulation. The Minister recommendation was TDS 500 mg/I. However, well 1 had a hazardous state of pollution because it used water that seeps into the soil. A well 1 still had good water condition since there was fields rice around it while the aquifers of well 2 were not polluted because it was shrouded by hard layers. This means the quality of well 2, in a longer period, was better than the quality of well 1.