Adams Morgan Water Hardness & Quality Report (2026)

Adams Morgan, Washington, DC, in the District of Columbia — a District of Columbia neighborhood adjacent to Columbia Heights and Woodley Park in northwest Washington — receives its water from DC Water, drawing from the Potomac River at the Washington Aqueduct (Dalecarlia and Georgetown reservoirs, District of Columbia) through the DC Water distribution system.

The moderately hard 120.5 mg/L hardness and TDS of 284.7 mg/L reflect the Washington DC Potomac River supply's moderate calcareous character — somewhat harder than the Fairfax Water Potomac-fed Vienna VA (85.5 mg/L), reflecting the DC Washington Aqueduct's different treatment and distribution characteristics from the Fairfax WTP. The Potomac River at the Washington Aqueduct drains the Virginia Blue Ridge (Precambrian Catoctin Greenstone — mostly insoluble), Triassic Culpeper Basin calcareous redbeds (moderate hardness contributor), and Cambrian Conococheague Formation (calcareous), producing the moderately hard DC supply.

At 120.5 mg/L, Adams Morgan's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling is appropriate. The PFAS level of 8.1 ppt warrants a certified reverse osmosis drinking water filter — the Washington DC metro PFAS complex from multiple Department of Defense facilities (Andrews Air Force Base, Bolling AFB) and the Potomac River PFAS background contribute to Adams Morgan's elevated readings.