The purpose of this research is twofold: (1) to demonstrate the effectiveness of GIS and spatial analysis as a tool for investigating groundwater contamination; and (2) to show the need for regular water quality testing of private wells. The research was conducted using secondary data freely available to the public and well construction records obtained from the Guilford County Environmental Health Department. The results of this study show GIS to be useful in the study of groundwater contamination and confirm the need for regular water quality tests of private wells. Because regular testing is currently not required, it is rarely done. Water from wells involved in this study was only tested after construction of the well or as a result of an ancillary event at the request of a government agency. Analysis revealed leaking underground storage tanks as the primary source of known groundwater contamination in Guilford Country. Gasoline, heating oil and diesel fuel were the major contaminates. Although counter intuitive, as the impervious surface area increased, so did the incidents of groundwater contamination.