Silver Spring Water Hardness & Quality Report (2026)

Silver Spring, Maryland, an unincorporated community in Montgomery County immediately north of the Washington DC boundary — the largest unincorporated community in the United States — draws its municipal water supply from the Potomac River via the Washington Suburban Sanitary Commission (WSSC Water), treating Potomac River water at the Potomac and Patuxent water filtration plants serving Montgomery and Prince George's Counties. Silver Spring is in the core urbanized inner Montgomery County WSSC service zone. Water hardness in Silver Spring measures 162 mg/L — classified as hard.

Silver Spring's hard supply reflects the Potomac River watershed's diverse Appalachian geology. The Potomac River at the Great Falls/WSSC intake drains: the Shenandoah Valley carbonates (Ordovician Beekmantown Group, Cambrian Conococheague Limestone — highly calcareous limestone and dolomite of the Virginia–West Virginia Valley and Ridge); the Blue Ridge (Proterozoic Catoctin metabasalt and Weverton Quartzite — calcium-poor contribution); and the Piedmont (Proterozoic Glenarm Series phyllite and schist — minor calcareous content). The dominant calcareous Shenandoah Valley limestone and dolomite drainage in the upper Potomac watershed produces the moderately hard 162 mg/L supply reaching Silver Spring.

At 162 mg/L, Silver Spring residents face regular hard water challenges. Scale deposits form on faucet aerators, showerheads, and appliances within weeks — monthly descaling with citric acid solution is standard maintenance. WSSC Water consistently delivers water meeting all Maryland MDE and EPA Safe Drinking Water Act requirements.