Merced Water Hardness & Quality Report (2026)

City of Merced Municipal Utilities Department serves over 84,000 residents in Merced County, California's Central Valley. The water supply is entirely groundwater sourced from 13 production wells tapping the San Joaquin Valley Groundwater Basin, specifically the Merced Subbasin. Water is extracted from aquifers and undergoes treatment at wellhead facilities for disinfection, corrosion control, and contaminant removal before distribution to historic downtown districts, neighborhoods around UC Merced, and broader communities. Annual Consumer Confidence Reports (CCRs) are published on the city's website by July 1 each year, available in English, Spanish, and Hmong.

Merced's groundwater flows through thick sequences of alluvial sediments and older sedimentary formations, including Pliocene-age deposits such as the Tulare Formation with its Corcoran Clay member and permeable sand lenses derived from Sierra Nevada erosion. These geological layers — laid down when the region was an ancient inland sea and later filled by river sediments — contribute dissolved minerals from limestone-rich strata and evaporitic sediments, resulting in elevated calcium and magnesium content. This mineralised profile characterises the supply as hard, typical of Central Valley groundwater.

Hard water causes significant scale buildup in pipes, water heaters, dishwashers, washing machines, and faucets, increasing energy costs by up to 50% and shortening appliance life. Maintenance involves regular vinegar descaling for fixtures, magnetic descalers or polyphosphate feeders for pipes, and annual water heater flushing. A whole-house water softener is strongly recommended. City water meets federal and state legal standards per CCRs, though it exceeds health guidelines for arsenic, uranium, and hexavalent chromium in 8 parameters due to natural groundwater leaching. Treatment includes chlorination, fluoride addition, and pH adjustment for corrosion control.