By Elizabeth Zach, RCAC staff writer

Glass of waterAlthough the U.S. federal government has monitored the country’s groundwater for the last 30 years, scientists say that only now can they begin to understand long-term pollution in the largest aquifers.

The U.S. Geological Survey’s National Water Quality Assessment says concentrations of chloride and sodium are on the increase, and in California, nitrate levels are climbing, according to Circle of Blue.

The study is important because many Americans rely on groundwater for their drinking water. About 25 percent of those people—numbering about 42 million—use unregulated household wells.

The study of groundwater is hampered, however because it tracks a limited number—only 25—contaminants, including pesticides, heavy metals, and nutrients. Toxic PFAS compounds, or perfluoroalkyl substances, which scientists believe can cause developmental problems and increase cancer risk, are not included. Moreover, the studies focus on metropolitan areas, and excludes Superfund sites.

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