The uncontrolled abstraction of groundwater aquifers in arid and semi-arid regions, such as Iran, can cause serious consequences to these vulnerable resources, including pollution. Therefore, monitoring the groundwater quality in these areas is of great importance. This study aimed to assess the groundwater quality for potable uses and determine the physicochemical properties of groundwater in Fasa Plain, located in Fars Province, southern Iran. To achieve this, 204 well water samples were collected during 2018 and 2019, and their physicochemical parameters were analyzed. The water quality index was also calculated, and the geographic information system (GIS) was applied to produce the numerical spatial distribution of the variables using analytical outcomes. The maps were drawn using the GIS interpolation method with the lowest error. The analysis results indicated that the concentration of all parameters approximately all over the plain in both years was within the allowable range of drinking water according to the World Health Organization. Additionally, the increased rainfall in the second year resulted in an improvement in water quality. The water quality index values revealed that in 2018, 76.05% and 23.95% of the aquifer area were classified as excellent and good quality, respectively. In 2019, these values were 89.62% and 10.38%, respectively. However, there are signs of the vulnerability to pollution by fertilizers and wastewater especially in southern areas of the plain. Therefore, proper management and prohibiting unnecessary utilization of this water resource should be fulfilled to prevent a decline in water quality.