Auburn Water Hardness & Quality Report (2026)

Auburn, California, in Placer County — the Placer County seat adjacent to Roseville and Folsom in the north California Sierra Nevada foothills — receives its water from the South Placer Municipal Utility District, drawing from the North Fork American River or Folsom Lake (Placer County) through the north California foothill distribution.

The very soft 35 mg/L hardness and very low TDS of 71.7 mg/L reflect the north California Placer County Sierra Nevada foothill supply's very soft character — driven by the direct Sierra Nevada granitic watershed of the American River with its insoluble Cretaceous granite bedrock yielding almost no mineral dissolution, typical of the Sierra Nevada foothills water supply (compare Hayden ID: 28 mg/L — similar pattern from granite mountain supply). The North Fork American River at Placer County — Cretaceous Sierra Nevada batholith granite (insoluble — primary dilutant, dominant character), minor Jurassic metamorphic country rock (slightly calcareous — trace contributor), and Quaternary Sierra Nevada granitic alluvium (insoluble).

At 35 mg/L, Auburn's water is very soft — no scale buildup, appliances last their full service life, and no softening is needed. Water is safe for all uses. The PFAS level of 3.0 ppt is below the EPA advisory threshold — one of the lowest readings in this dataset. Standard carbon block filter is sufficient for drinking water quality in Auburn.