North Fair Oaks Water Hardness & Quality Report (2026)
Water Hardness
4.1 grains per gallon
Source
mixed
pH Level
7.5
neutral = 7.0
Lead
0.003 mg/L
✓ Below action level
TDS
160.5 mg/L
Est. Daily Cost
$0.19
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 North Fair Oaks, your appliances are currently losing 9% efficiency due to mineral buildup.
| Appliance | In North Fair Oaks | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 7.3 yrs | 8.5 yrs | -14% |
| Washing Machine | 11 yrs | 12 yrs | -8% |
| Water Heater | 12.8 yrs | 15 yrs | -15% |
Regional Water Comparison
How North Fair Oaks compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ North Fair Oaks, California | 69.5 mg/L | 4 ppt | 🟡 Moderately Hard | mixed |
| Menlo Park, California | 69 mg/L | 4 ppt | 🟡 Moderately Hard | mixed |
| Redwood City, California | 178 mg/L | 7.2 ppt | 🟠 Hard | mixed |
| East Palo Alto, California | 145 mg/L | 6.2 ppt | 🟠 Hard | mixed |
| Stanford, California | 103.5 mg/L | 5 ppt | 🟡 Moderately Hard | mixed |
National Benchmark
How North Fair Oaks compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ North Fair Oaks | 69.5 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes North Fair Oaks's Water Unique?
Local geology and source profile
North Fair Oaks, California, in San Mateo County — an unincorporated San Mateo County community adjacent to Redwood City and Menlo Park on the west San Francisco Bay peninsula — receives its water from California Water Service or local utilities, drawing from San Francisco Public Utilities Commission (SFPUC) Hetch Hetchy water (San Mateo County) through the Bay peninsula distribution.
The moderately soft 69.5 mg/L hardness and TDS of 160.5 mg/L reflect the San Francisco peninsula SFPUC Hetch Hetchy supply's softened Sierra Nevada granite character — consistent with other peninsula San Mateo County communities (Menlo Park: ~68 mg/L; San Carlos: ~70 mg/L). The SFPUC Hetch Hetchy system draws from Yosemite Valley — Mesozoic Sierra Nevada Batholith (granite — nearly insoluble, primary supply), Precambrian crystalline basement (insoluble), and minor Triassic-Jurassic intrusive (insoluble). The insoluble Sierra Nevada granite produces the moderately soft Bay peninsula supply.
At 69.5 mg/L, North Fair Oaks' water is moderately soft — light scale forms slowly in appliances, dishwashers remain efficient, and bathroom fixtures need occasional cleaning. Semi-annual descaling is appropriate. The PFAS level of 4.0 ppt warrants a certified drinking water filter — the San Mateo County Bay peninsula tech-industrial corridor and the legacy Moffett Field Naval Air Station (Santa Clara County — AFFF) PFAS plume contribute to North Fair Oaks' readings.
Geology & Source: North Fair Oaks in San Mateo County draws from the California Water Service on San Francisco Public Utilities Commission (SFPUC) Hetch Hetchy water (San Mateo County, west San Francisco Bay peninsula) — Hetch Hetchy drains Yosemite (Mesozoic Sierra Nevada Batholith — granite, nearly insoluble) — California San Mateo County SFPUC Hetch Hetchy Sierra Nevada granite watershed produces moderately soft water at 69.5 mg/L with TDS 160.5 mg/L.