According to the U.S. Geological Survey, an estimated 258 million people nationwide, or 86% of the U.S. population, relied on public water supplies for their household use in 2005 (USGS, 2013). The remaining population obtains their water from different sources, such as a domestic self-supply well. However, the spatial distribution of water supply systems has not been compiled. Mapping where these people are located can be done within a GIS (Geographic Information System). The approach used takes into account a number of different attributes gathered from the United States Census Bureau for the block group and block shapes within the Delaware River Basin.