NoMa Water Hardness & Quality Report (2026)

NoMa, a neighborhood in Washington, D.C., receives its water from the D.C. Water and Sewer Authority (DC Water), which serves approximately 681,000 residents across the District. Water is sourced primarily from the Potomac River, drawn from intakes upstream near Great Falls and Little Falls. It undergoes treatment at the Washington Aqueduct facilities, including the Dalecarlia and Potomac River treatment plants operated by the U.S. Army Corps of Engineers, before distribution through DC Water's extensive network. NoMa falls within DC Water's full service area, sharing the same supply as the broader city.

The Potomac River watershed spans 14,670 square miles across West Virginia, Virginia, Maryland, and D.C., with headwaters in the Appalachian Mountains. The geology features Paleozoic carbonate rock formations including the Ordovician Beekmantown Limestone and Cambrian Waynesboro Formation, alongside metamorphic and sedimentary layers in the Piedmont region. These dissolve readily, imparting a moderately mineralised character due to elevated calcium and magnesium from limestone dissolution, with seasonal runoff modulating ion concentrations.

At 119.84 mg/L (moderate hardness), limescale buildup affects coffee makers, kettles, dishwashers, faucets, showerheads, and water heaters, clogging screens and heating elements over time. Regular vinegar descaling and scale-inhibiting filters are recommended; a water softener is optional but beneficial for high-use households to extend appliance life and improve soap efficiency. DC Water's 2025 Consumer Confidence Report confirms compliance with EPA standards, including lead and copper rule adherence via corrosion control. Trace disinfection byproducts and chromium-6 have been detected near health guidelines; sodium averages 126 ppm (78–175 ppm range). Treatment involves coagulation, sedimentation, filtration, chloramination, and fluoridation.