Maryland’s largest water utility has temporarily lowered the fluoride concentration in its drinking water, citing supply chain disruptions linked in part to the conflict in Iran. Starting Tuesday afternoon, WSSC Water reduced fluoride levels from approximately 0.7 milligrams per liter to 0.4 milligrams per liter at its Potomac and Patuxent filtration plants. This change affects about 1.9 million residents in Montgomery and Prince George’s counties.

The reduction is attributed to operational challenges faced by a major hydrofluorosilicic acid supplier based in Israel, a chemical used for fluoridation in public water systems. WSSC Water officials indicated that while deliveries continue, the volume is below normal levels, complicating their ability to maintain prior fluoride dosing.

Despite the adjustment, the utility emphasized that the tap water remains safe to consume. “There’s no impact on water quality,” said WSSC Water spokesperson Luis Maya. The lowered fluoride concentration entails a reduced capacity to prevent tooth decay, but does not present a health hazard.

Fluoride is commonly added to public water supplies as a preventive measure against dental cavities, a practice endorsed by the Centers for Disease Control and Prevention and the American Dental Association, though it is not federally or state-mandated. Marc Edwards, a civil engineering professor at Virginia Tech who studies drinking water, noted that the decrease will slightly reduce cavity prevention benefits. He described fluoridation as a cost-effective public health tool that benefits the population regardless of individual dental hygiene or access to treatments.

WSSC Water advised customers, particularly parents and those at higher risk of dental problems, to consult dentists about alternative fluoride sources during the temporary shortage. The utility has not announced when it expects to restore fluoride levels to previous standards.

Meanwhile, the Army Corps of Engineers, which operates the Washington Aqueduct water treatment facilities serving about one million people in Washington, D.C., and nearby Northern Virginia counties, reported no disruptions. The Aqueduct draws water from the Potomac River and supplies wholesale water to DC Water, Fairfax Water, and Arlington County.

“Despite reports of local fluoride supply disruptions, the Washington Aqueduct’s water treatment remains unaffected,” said Cynthia Mitchell, a Corps spokeswoman. She confirmed that treated water continues to meet all Environmental Protection Agency standards and that there have been no operational changes due to supply issues. The Corps is closely monitoring supply chains to ensure uninterrupted service at its plants producing an average of 150 million gallons daily.

The Maryland and D.C. regional water authorities appear to be managing the supply constraints differently, with Maryland’s largest utility reducing fluoride dosing, while the Washington Aqueduct maintains normal treatment levels amid the ongoing geopolitical tensions affecting chemical suppliers.