Novato Water Hardness & Quality Report (2026)

The North Marin Water District (NMWD) provides water to Novato and surrounding areas in Marin County, California. The utility's primary source is treated water purchased from the Sonoma County Water Agency (SCWA), which operates six Ranney collector wells and seven conventional wells at Wohler and Mirabel, plus three additional wells in the Santa Rosa Plain. Water is extracted from groundwater aquifers recharged by subsurface flows and Russian River infiltration. NMWD adds chlorine for disinfection and sodium hydroxide to adjust pH to 8.3 for corrosion control.

Novato's water supply originates from the Russian River alluvial aquifer, a Quaternary-age formation of gravel, sand, and silt deposits adjacent to the Russian River. The naturally filtered groundwater passes through layers of anthracite and garnet sand, then granular activated charcoal to remove impurities. The aquifer's mineral composition — derived from weathering of surrounding rock and mineral-rich alluvial deposits — contributes moderate to elevated levels of dissolved calcium and magnesium, making the supply hard. The SCWA source water benefits from natural filtration through gravel beds 80–100 feet below the river channel.

At this hard hardness level, Novato residents can expect noticeable scale buildup on fixtures and reduced soap lathering. Water heaters, dishwashers, and washing machines are particularly vulnerable to limescale accumulation, which reduces efficiency and shortens appliance lifespan. Mineral deposits may clog aerators and reduce water pressure over time. A water softener is recommended, especially for households with high water usage or sensitive appliances. Regular descaling of fixtures and periodic plumbing maintenance help mitigate mineral buildup. Novato's water meets or exceeds all federal and state drinking water standards, confirmed by the 2023 Annual Water Quality Report.