Coronado Water Hardness & Quality Report (2026)

Coronado, California, in San Diego County — a distinctive peninsula city on San Diego Bay connected to the mainland by the iconic Coronado Bridge — receives its municipal water exclusively through the Coronado Municipal Water District, which purchases 100% of its supply from the San Diego County Water Authority (SDCWA). Coronado has absolutely no local water sources; every drop arrives through regional import infrastructure. SDCWA blends water from the Colorado River Aqueduct (managed by the Metropolitan Water District of Southern California) and the California State Water Project (Sacramento-San Joaquin Delta) at treatment facilities before distributing throughout San Diego County.

The moderate 138 mg/L hardness is characteristic of SDCWA's blended imported supply. Colorado River water at the Lake Havasu intake (Aqueduct source) is substantially harder (~250–300 mg/L) from transit through the Colorado Plateau's extensive carbonate formations. State Water Project water from northern California is considerably softer (~100–130 mg/L) from its Sacramento Valley and Sierra Nevada origins. SDCWA's treatment and blending process — along with lime softening at regional treatment plants — moderates the Colorado River's high hardness, producing the moderate-range finished water distributed to Coronado households.

At 138 mg/L, Coronado's water is moderately hard — noticeable but manageable for everyday use. Appliances scale gradually over months, rinse aid in the dishwasher prevents mineral film on glassware, and faucet aerators benefit from quarterly cleaning. The water's mineral taste is mild at this level. Quarterly descaling of kettles and coffee machines keeps appliances in good operating condition. The PFAS level of 5.9 ppt is moderate for a Southern California coastal community — Navy and military installations on the Coronado peninsula contribute to the regional PFAS background, and a certified drinking water filter is a prudent choice for daily water consumption.