Tempe Water Hardness & Quality Report (2026)

The City of Tempe Water Utility serves approximately 200,000 residents across Tempe and surrounding areas in Maricopa County, Arizona. The utility sources water from the Salt River Project (SRP), which operates reservoirs including Lake Pleasant and Theodore Roosevelt Lake, supplemented by groundwater from local aquifers. Treatment occurs at multiple facilities before distribution through the municipal system. Tempe's water meets all federal, state, and local water quality standards.

Tempe's supply originates from the Salt River watershed and local Basin and Range aquifers in central Arizona. The underlying geology comprises Precambrian granite and metamorphic basement rocks overlain by Tertiary volcanic and sedimentary formations and Quaternary alluvial deposits. Calcium and magnesium minerals dissolve naturally from these rock formations into both surface water and groundwater, resulting in a hard water supply typical of Arizona's desert hydrology.

Hard water in Tempe commonly causes scale buildup in water heaters, dishwashers, and washing machines, along with reduced soap and detergent effectiveness and mineral deposits on fixtures. Appliances require more frequent maintenance and descaling. Many households benefit from point-of-use or whole-house water softeners, particularly for laundry and bathing. Regular flushing of water heaters and use of chelating agents in dishwashers can mitigate accumulation. Tempe's water quality reports confirm compliance with Safe Drinking Water Act standards; the utility monitors for lead and copper with results in annual Consumer Confidence Reports available through the City of Tempe's Public Works department. pH levels and disinfection byproducts remain within regulatory limits, with conventional treatment including coagulation, sedimentation, filtration, and chlorination.