Drinking private well water: Groundwater quality and management of wells in southern Alabama.

Private wells provide a source of household water for over 40 million people in the United States and an estimated 1 million people in the Coastal Lowlands Aquifer system along the Gulf of Mexico. Well water quality is dependent on the local geology and factors that contribute to anthropogenic contamination from the surface. Here, we evaluated groundwater quality and well management in southern Alabama, USA, to better understand factors that influence exposures through drinking water from private wells. The most common constituents that exceeded USEPA primary or secondary human health benchmarks were pH (92%), and total coliform (TC) (25%), followed by Fe (7%), Pb (6%), nitrate (1%), and As (1%). Most wells (68%) also displayed temporal changes in the number of exceedances, often showing positive for TC during one sampling campaign and negative in another, while the secondary standard for pH (6.5-8.5) was consistently not met. We also found that the common choices of water treatment did not protect against the most common water quality exceedances. Our results underscore the need to understand well water quality coupled with management practices when assessing potential exposures to the private well population through drinking water.