Aberdeen Water Hardness & Quality Report (2026)

Aberdeen, Washington, in Grays Harbor County — a Grays Harbor County city adjacent to Hoquiam and Cosmopolis on Grays Harbor at the mouth of the Chehalis River in southwest Washington — receives its municipal water from the Aberdeen Water Division, drawing from the Wynoochee Reservoir (Grays Harbor County) through the Aberdeen water treatment plant.

The very soft 34 mg/L hardness and very low TDS of 64.2 mg/L reflect the Olympic Mountain watershed's nearly insoluble volcanic character — consistent with other southwest Washington Olympic Peninsula supplies. The Wynoochee watershed drains the Olympic Mountains — Eocene Hoh Rock Assemblage basalt (insoluble oceanic basalt — very low mineral solubility), Oligocene Quinault Formation siliceous turbidite (insoluble), and Quaternary glacial outwash (insoluble quartz sand from the Olympic Mountain ice fields). The entirely insoluble Olympic Mountain volcanic and siliceous geology produces the very soft southwest Washington supply.

At 34 mg/L, Aberdeen's water is very soft — essentially no scale forms, soap lathers abundantly, and appliances maintain excellent efficiency. Annual descaling is sufficient. The PFAS level of 2.0 ppt is very low — the Grays Harbor County industrial timber and port corridor contributes modest PFAS, and the Olympic Mountain headwaters are essentially pristine.