This study examines the quality of drinking water using Fuzzy-AHP south of Firozabad, in the Darenjan watershed Fars province. The study area to determine water quality parameters such as total hardness, calcium, magnesium, sodium, conductivity, sulfate and total dissolved solids were examined. In this study, using the Kriging (Gaussian models, spherical, circular and exponential) each parameter zoning map was, determined and then, using the fuzzy membership function map of each of the parameters affecting the quality of drinking water was prepared. Then, the weight of each layer was determined by using Analytical Hierarchy Process (AHP), and finally water quality map was prepared in GIS. The results indicated that only 4.38 percent of the area has very good quality, good quality 23.33%, 64.01% and 8.29% percent of the average quality of water has poor quality. On the other hand, to determine the relationship between water quality and topographic features in the study area, landforms map was prepared by using topographical position indicator. It was also found that the highest water quality is available in the river landforms, valleys, ridges and upstream drainage. While the lowest quality of drinking water in the plains and piedmont of the study area is located.