Geographic Information Systems (GIS) software is used to analyze rainwater harvesting potential in Escambia County, Florida, USA. The approach presented can be replicated using LiDAR data, and the infrared spectrum of National Agriculture Imagery Program (NAIP) imagery. GIS surface maps are analyzed in combination with local utility consumption data to determine potential reductions in potable water consumption for households. The results indicate an extensive urban catchment of rooftop surfaces, and commensurate potential for rainwater harvesting and stormwater attenuation. Sixty two percent of the households analyzed consumed less water than could be potentially harvested. The remaining 38% consumed more water than could be potentially harvested. There are noted and significant differences between the two sample populations, including differences in water consumed and roof size. A comparison of lot size between the two sample populations did not yield any significant difference. The conclusions indicate that the widespread implementation of rainwater harvesting could substantially reduce potable water use in urban areas, and are of use to policy makers, planners, engineers and property owners everywhere.