About 3,600 people in Daviess County rely on private domestic water wells. The Ohio River alluvium is the best source of groundwater in the county; nearly all drilled wells from depths of less than 150 feet in the alluvium are adequate for domestic use, with most wells yielding more than 50 gallons per minute, and some wells yielding as much as 750 gallons per minute. In central and southern Daviess County, most wells less than 300 feet deep that penetrate sandstone are adequate for a domestic supply. In several small, localized areas in southern Daviess County, most wells yield little or no water. Generally, groundwater is hard to very hard, and iron and salt may be present in objectionable amounts. Groundwater in deep wells often becomes too mineralized to use.