North Tustin Water Hardness & Quality Report (2026)

North Tustin, California, in Orange County in the foothills east of Tustin and Irvine, receives its municipal water from the East Orange County Water District (EOCWD) and Serrano Water District, both of which blend imported water from the Metropolitan Water District of Southern California (MWD) with locally produced groundwater from the Orange County Groundwater Basin. MWD imports water from the Colorado River Aqueduct and the State Water Project (Sacramento-San Joaquin Delta), while the OC Basin is recharged primarily through the Santa Ana River and managed aquifer recharge facilities operated by the Orange County Water District (OCWD).

The moderate 134 mg/L hardness is a characteristic outcome of the blended supply strategy used throughout northeastern Orange County. Colorado River water is inherently hard (typically 250–300 mg/L) from its transit through the Jurassic and Cretaceous carbonate formations of the Colorado Plateau. State Water Project water from northern California is considerably softer (~100–130 mg/L). Local OC Basin groundwater — recharged through Santa Ana River alluvium with calcareous Tertiary sediment contributions from the Santa Ana Mountains — registers in the moderate hardness range. EOCWD's treatment and blending process averages these sources, producing consistent moderate hardness throughout North Tustin.

At 134 mg/L, North Tustin's water is moderately hard — typical for southern Orange County communities in the foothills service zone. Appliances scale gradually over months, rinse aid is helpful in the dishwasher, and faucet aerators benefit from quarterly cleaning. The water's taste profile is mild and pleasant at this mineral level. Quarterly descaling of kettles and water heater elements maintains appliance efficiency. The PFAS level of 5.8 ppt is moderate for Orange County — a certified point-of-use filter is a practical choice for residents preferring an added layer of protection for drinking water.