Granite Bay Water Hardness & Quality Report (2026)

Granite Bay, California, in Placer County — an affluent unincorporated Placer County community on the northeastern shore of Folsom Lake, a premier horse country and equestrian community north of Folsom in the Sierra Nevada foothills corridor — receives its municipal water from the San Juan Water District or Placer County Water Agency (PCWA), which draws from the American River at Folsom Lake (through the Folsom Dam and the Folsom South Canal / American River Canal distribution) and from State Water Project deliveries.

The very soft 30 mg/L hardness and very low TDS of 60.4 mg/L reflect the American River's pristine Sierra Nevada granite watershed character. The American River drains the northern Sierra Nevada from the high-altitude headwaters (including the American River Canyon, Lake Tahoe basin, and the Desolation Wilderness) through terrain dominated by the Cretaceous Sierra Nevada Batholith — massive granodiorite, tonalite, and diorite with essentially no carbonate minerals. Granite dissolves extremely slowly in cool mountain water, producing the very soft, very low-mineral water characteristic of all American River-Folsom Lake supply systems throughout Sacramento and Placer Counties.

At 30 mg/L, Granite Bay's water is very soft — excellent for household use. Scale essentially never forms, soap lathers abundantly, and appliances maintain maximum efficiency. Annual descaling is more than sufficient. The PFAS level of 2.9 ppt is excellent for the Sacramento-Placer foothills — the Mather Air Force Base (former — in Sacramento County, American River watershed — a documented AFFF source), Beale AFB (Yuba County, Yuba-Feather River watershed), and the Sacramento Valley minimal direct military-industrial PFAS sources in the American River headwaters produce this moderate PFAS background.