Mountain View Water Hardness & Quality Report (2026)

The City of Mountain View Public Works Department manages water and sewer services for approximately 85,000 residents in Mountain View, California, in Santa Clara County. Water sources include local groundwater from the Santa Clara Groundwater Basin via valley floor wells and imported surface water from the Sacramento-San Joaquin Delta, delivered through the Santa Clara Valley Water District (Valley Water). Treatment occurs at facilities managed by Valley Water and local partners, with distribution via the city's infrastructure.

The primary watershed for imported water is the Sacramento-San Joaquin Delta, fed by Sierra Nevada snowmelt through the State Water Project and Central Valley Project. Local groundwater taps the Santa Clara Groundwater Basin, an alluvial aquifer beneath the Santa Clara Valley, where sedimentary and limestone formations dissolve calcium and magnesium to produce a harder character from wells. Imported surface water remains moderately mineralised due to less rock interaction in conveyance systems, and blending the two sources yields water with variable chemistry.

As a moderately hard supply, water causes moderate scale buildup in pipes, water heaters, dishwashers, washing machines, and coffee makers where limescale accumulates. Annual flushing of water heaters, vinegar soaks for showerheads, and scale inhibitors are recommended. A water softener is advised for households noticing soap scum, dry skin, or spotting on dishes. The 2024 Consumer Confidence Report notes lead detections at 10% of sites above 7.7 ppb (below the 15 ppb Action Level) and Chromium-6 averaging 1 ppb; treatment involves filtration, chloramine disinfection, and corrosion control. The report is available at mountainview.gov.