Saint Charles Water Hardness & Quality Report (2026)

The Charles County Government Department of Public Works Utilities operates the water supply for St. Charles (also known as the Waldorf area) in Charles County, Maryland. The system draws from groundwater aquifers, primarily the Potomac Group aquifers including the Patuxent and Aquia formations. Key treatment facilities include the Mattawoman-Woodville and Indian Head Water Treatment Plants, together serving over 150,000 residents across Charles County. Consumer Confidence Reports are published annually on the county's website, detailing system-wide water quality compliance.

The supply originates from the Southern Maryland Coastal Plain aquifers, part of the Atlantic Coastal Plain physiographic province. Water infiltrates through unconsolidated sediments and limestone-rich formations including the Calvert, Nanjemoy, and Pamunkey Groups of Eocene to Miocene age. These calcareous sands and shell-bearing sedimentary rocks dissolve calcium and magnesium as water percolates through, yielding a hard supply. Natural base exchange in some aquifer layers provides partial softening, but the geology generally imparts significant mineralization.

Hard water causes visible scale buildup in pipes, fixtures, and appliances, reducing efficiency and lifespan. Water heaters, dishwashers, washing machines, and coffee makers are most affected, with mineral deposits increasing energy use by up to 20–30% and leading to frequent breakdowns. Regular vinegar descaling, installing sediment filters, and flushing water heaters biannually are recommended maintenance steps. A whole-home water softener is strongly recommended to prevent stains, improve soap lathering, and extend plumbing life. Treatment includes aeration, greensand filtration for iron removal, chlorination, and fluoride addition; pH typically runs 7.2–7.8.