Brentwood Water Hardness & Quality Report (2026)

The City of Brentwood Water Utility serves approximately 63,000 residents in Brentwood, Contra Costa County, California (150 City Park Way, Brentwood, CA 94513; contact: 925-516-5441, operations@brentwoodca.gov). Water is sourced from purchased surface water originating in the Sacramento-San Joaquin Delta, treated at the Brentwood Water Treatment Plant, which delivered water to over 21,000 connections in 2024. The utility complies with federal and state standards, as detailed in its annual Water Quality Fact Sheets and 2024 Consumer Confidence Report available on brentwoodca.gov.

The supply originates from the Sacramento-San Joaquin Delta watershed, a vast estuarine system fed by Sierra Nevada snowmelt and Central Valley rivers. Underlying geology includes Mesozoic Franciscan Complex rocks and thick Cenozoic sedimentary layers of the Great Valley Sequence, with aquifers in Quaternary alluvium rich in carbonate minerals from eroded limestones and dolomite fragments in the Diablo Range foothills. Natural dissolution of these minerals, exacerbated by low-flow concentration in reservoirs like the Delta, imparts a characteristically hard character with elevated calcium and magnesium content.

Very hard water promotes heavy limescale buildup in water heaters, dishwashers, washing machines, and pipes — expect frequent descaling and higher energy bills, with boilers and fixtures showing white deposits quickly. Maintenance involves vinegar rinses for taps, annual heater flushes, and low-flow aerators. A salt-based ion exchange softener or salt-free conditioner is strongly recommended for households. The 2024 report confirms full compliance with primary standards; potential concerns include elevated Chromium-6 and TTHMs exceeding health advocacy levels alongside traces of 1,1-Dichloroethane, Heptachlor epoxide, 1,2-Dichloropropane, and Chloromethane per third-party analysis.