Arlington County Water water, explained

Hardness: 7 to 9 grains per gallon

Arlington reported a 2025 average of 142 mg/L, about 8 grains per gallon. Anything above 7 grains per gallon is classified as hard. In practice that means scale on fixtures and shower glass, spotted dishes and mineral buildup inside water heaters and tankless units.

Disinfectant: Chloramine

Arlington reported a 2025 average chloramine residual of 2.1 mg/L. Catalytic carbon, not standard carbon, is what removes it reliably.

Seasonal changes: The Washington Aqueduct switches to free chlorine for a few weeks each spring. Expect a stronger chlorine smell and taste during the flush.

PFAS

Utilities that draw from the Potomac have reported low-level PFAS detections in routine monitoring. EPA finalized limits for PFOA and PFOS in 2024. An under-sink reverse osmosis system certified to NSF/ANSI 58 is the practical fix at the tap you drink from.

Lead

Arlington has an active program to find and replace lead service lines. Homes built before the mid-1950s are the most likely to still have one. Lead does not come from the treatment plant. It comes from older home plumbing: pre-1986 solder, older brass fixtures and, in some neighborhoods, lead service lines. A point-of-use filter certified to NSF/ANSI 53 for lead, or reverse osmosis, addresses it at the tap.

What we recommend on Arlington County water

A whole-home softener with catalytic carbon handles hardness and chloramine together. Under-sink reverse osmosis covers drinking water, and it is the realistic option for Arlington condos where a whole-home install is not possible.

Figures checked September 2026 against Arlington County water quality reports. Utilities update reports annually; if you see a newer figure, tell us and we will update this page.