Conducted from June 2002-January 2003, the study aimed to achieve a better understanding of private drinking water wells in incorporated Iowa towns not served by a public water supply system. Water samples were analyzed by the University of Iowa Hygienic Laboratory (duplicate samples analyzed at USGS laboratories) for common use pesticides, nitrogen compounds, inorganics, bacteria, and VOCs. The study design contained a random and focused component. * Random Study Methodology: Approximately 103 drinking water wells from towns that did not have a public water supply were selected. A weighted distribution of households from US Census data was employed to select wells (i.e.- towns with a higher number of households stood a greater chance of having a well selected). County environmental health specialists visited these towns, located randomly generated points on maps, and found the nearest building to draw a water sample. Fifty distinct towns had one or more wells sampled. * Focus Study Methodology: The focus study employed the use of existing databases of potential contamination sources to intensively sample 15 communities. Selection criteria for these towns considered: towns utilizing private septic systems, existence of underground storage tanks, location of agricultural grain and chemical storage dealerships, regional hydrogeology, active and closed landfills, feedlots, railroad systems, industries in violation of wastewater permit applications (including stormwater permits), nearby uncontrolled sites identified by the Iowa Department of Natural Resources (IDNR), and Resource Conservation and Recovery Act (RCRA)/Superfund sites.