Rose Hill Water Hardness & Quality Report (2026)

Rose Hill, Virginia, in Fairfax County — an unincorporated Fairfax County community in the Alexandria-Annandale-Kingstowne southern Fairfax corridor, part of the densely urbanized inner Northern Virginia Washington DC suburbs — receives its municipal water from Fairfax Water, which draws from the Occoquan Reservoir (Bull Run watershed) and the Potomac River at the Griffith water treatment plant, the two primary sources for the Fairfax County metropolitan water authority.

The moderately hard 182 mg/L hardness and TDS of 458.2 mg/L reflect Fairfax Water's Occoquan-Potomac supply's Virginia Piedmont geological character. The Occoquan Reservoir watershed drains the Virginia Piedmont — terrain underlain by the Triassic Culpeper Basin (red-bed calcareous sandstone and shale — the Manassas Sandstone, Balls Bluff Siltstone), Precambrian gneiss and Cambrian calcareous metasediment. The Potomac River supply adds the broader watershed character (mixed Blue Ridge crystalline and Valley and Ridge carbonate). The combined Occoquan-Potomac supply produces the moderately hard water characteristic of Northern Virginia metro communities.

At 182 mg/L, Rose Hill's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and bathroom fixtures develop calcium deposits. Quarterly descaling is appropriate. The PFAS level of 9.5 ppt is very high and warrants a certified reverse osmosis drinking water filter — the Quantico Marine Corps Base, Fort Belvoir (US Army — Occoquan watershed), Andrews AFB, and the dense Northern Virginia defense-industrial complex all contribute to Fairfax County's extremely elevated PFAS readings throughout the Occoquan watershed.