THE QUALITY OF GROUNDWATER USED FOR PUBLIC SUPPLY IN THE CONTINENTAL UNITED STATES

What is the quality of groundwater used as a source of public supply in the continental United States (CONUS)? More specifically: Which constituents are most prevalent at elevated concentrations? How many people are potentially affected? What are the hydrogeologic and geochemical characteristics of the aquifers where elevated concentrations are observed? These questions were addressed by evaluating the quality of groundwater in 25 Principal Aquifers (PAs) that account for 84% of the groundwater used for public supply in the CONUS (89.6 million people on a proportional basis). PAs are regionally extensive aquifers or aquifer systems that can provide large volumes of water for human use. Each PA was sampled across its lateral extent using an equal-area grid, typically with 60 wells per PA. Samples were analyzed for 502 constituents, of which 374 had either a regulatory or non-regulatory human-health benchmark. In all but three PAs, the most frequently detected constituent at elevated concentrations was a geogenic constituent. At the CONUS scale, geogenic constituents are more prevalent (based on area) and potentially affect more people than anthropogenic constituents. The occurrence of elevated concentrations is affected by aquifer type (lithology, location, and climate), pH, redox, groundwater age, and land use. The findings from this study (Belitz and others, 2022) can be used by managers responsible for providing safe drinking water, regulators considering which constituents might require additional scrutiny, and researchers seeking to identify groundwater quality issues of relevance to human health.

Belitz and others, 2022, “Quality of Groundwater Used for Public Supply in the Continental United States: A Comprehensive Assessment,” Environmental Science and Technology – Water. doi.org: 10.1021/acsestwater.2c00390