Santa Rosa Water Hardness & Quality Report (2026)
Water Hardness
5.6 grains per gallon
Source
mixed
pH Level
7.6
neutral = 7.0
Lead
0.005 mg/L
✓ Below action level
TDS
239 mg/L
Est. Daily Cost
$0.25
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Santa Rosa, your appliances are currently losing 13% efficiency due to mineral buildup.
| Appliance | In Santa Rosa | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.4 yrs | 8.5 yrs | -25% |
| Washing Machine | 10.1 yrs | 12 yrs | -16% |
| Water Heater | 11.8 yrs | 15 yrs | -21% |
Regional Water Comparison
How Santa Rosa compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Santa Rosa, California | 95.5 mg/L | 4.8 ppt | 🟡 Moderately Hard | mixed |
| Rohnert Park, California | 123.5 mg/L | 5.6 ppt | 🟠 Hard | mixed |
| Windsor, California | 174 mg/L | 7.1 ppt | 🟠 Hard | mixed |
| Petaluma, California | 48.5 mg/L | 3.4 ppt | 🟢 Soft | mixed |
| Agua Caliente, California | 29 mg/L | 2.9 ppt | 🟢 Soft | mixed |
National Benchmark
How Santa Rosa compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Santa Rosa | 95.5 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Santa Rosa's Water Unique?
Local geology and source profile
Santa Rosa, California receives its municipal water supply through the City of Santa Rosa Water Division, supplied by the Sonoma County Water Agency (SCWA), which manages the Russian River surface water system. SCWA draws from the Russian River at intakes near Forestville, supplemented by Lake Mendocino (Coyote Valley Dam on the East Fork Russian River) and Lake Sonoma (Warm Springs Dam on Dry Creek) storage reservoirs in Mendocino and Sonoma Counties. Raw Russian River water is treated at SCWA's Geysers Road and Subregional Treatment Plants before distribution to Santa Rosa and other agency member agencies. Water hardness in Santa Rosa measures 95.5 mg/L — classified as moderately soft.
Santa Rosa's moderate softness reflects the geological character of the Russian River watershed in the California Coast Ranges. The Russian River drains the Franciscan Complex — a chaotic assemblage of Jurassic and Cretaceous blueschist, greywacke, mélange, and ophiolitic basalt typical of the Coast Ranges accretionary wedge terrain. These metamorphic and volcanic rock types are calcium-poor relative to carbonate sedimentary rocks, limiting mineral dissolution into surface water. The inland portions of the watershed also cross Coast Range Greenstone volcanic sequences, further constraining hardness. Some calcareous blocks within the Franciscan mélange contribute modest calcium, producing the moderately soft final supply.
At 95.5 mg/L, Santa Rosa residents experience light scale accumulation in household use. Faucet aerators and showerheads develop minor deposits over several months — quarterly descaling keeps them performing well. Dishwashers produce largely spot-free glassware with standard rinse-aid use, and hot water systems experience modest long-term scale build-up that does not require urgent attention. Sonoma County Water Agency consistently delivers high-quality water meeting all California State Water Resources Control Board and EPA standards, and the Russian River catchment benefits from active environmental stewardship.
Geology & Source: Mixed supply from the Russian River via Lake Mendocino and Lake Sonoma (Warm Springs Dam), managed by Sonoma County Water Agency, blended with local groundwater — the Russian River drains the Franciscan Complex mélanges, Coast Range Greenstone, and Coast Ranges ophiolite volcanic terrain, producing moderately soft supply at 95.5 mg/L.