Groundwater present in aquifers is a source drinking water for almost 150 million people in the United States. However, the use of groundwater for drinking is often limited by the presence of geogenic contaminants — elements that occur in groundwater because of natural water–rock interactions. Some geogenic contaminants, such as manganese, molybdenum and sulfate, are essential for human health in small quantities. But at high concentrations, these contaminants can damage organs, cause cancer or impair reproductive function.A multi-decadal analysis of geogenic contaminants across the lower 48 states arms water-resource managers and public health professionals with new information for protecting the health and
