Belmont Water Hardness & Quality Report (2026)
Water Hardness
10.3 grains per gallon
Source
mixed
pH Level
8.2
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
543.3 mg/L
Est. Daily Cost
$0.47
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 Belmont, your appliances are currently losing 23% efficiency due to mineral buildup.
| Appliance | In Belmont | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.8 yrs | 8.5 yrs | -55% |
| Washing Machine | 7.1 yrs | 12 yrs | -41% |
| Water Heater | 8.6 yrs | 15 yrs | -43% |
Regional Water Comparison
How Belmont compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Belmont, California | 176 mg/L | 7.1 ppt | 🟠 Hard | mixed |
| San Carlos, California | 163 mg/L | 6.8 ppt | 🟠 Hard | mixed |
| Foster City, California | 143 mg/L | 6.2 ppt | 🟠 Hard | mixed |
| Redwood City, California | 178 mg/L | 7.2 ppt | 🟠 Hard | mixed |
| San Mateo, California | 40.5 mg/L | 3.2 ppt | 🟢 Soft | mixed |
National Benchmark
How Belmont compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Belmont | 176 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Belmont's Water Unique?
Local geology and source profile
Belmont, California, in San Mateo County — a major mid-San Francisco Peninsula suburban community (Belmont is a significant San Mateo County city — a mid-Peninsula suburb adjacent to San Carlos and Foster City; Belmont is home of Notre Dame de Namur University (a Catholic liberal arts university on a beautiful hilltop campus overlooking the San Francisco Bay) and is situated in the heart of Silicon Valley's Peninsula technology corridor; Belmont has excellent access to CalTrain (the Peninsula commuter rail line connecting San Francisco to San Jose — CalTrain's Belmont station is one of the key mid-Peninsula stops)); Belmont is known for its hillside residential development and its proximity to the Crystal Springs Reservoir (one of the most significant water supply reservoirs in the San Francisco Bay Area), a diverse San Mateo County community with a primarily professional, tech industry, and diverse suburban family population, adjacent to San Carlos and Redwood City in the mid-Peninsula corridor — draws its municipal water supply via the California Water Service Company. Water hardness in Belmont measures 176 mg/L — classified as hard.
Belmont's hard supply reflects the mid-Peninsula San Mateo County Bay Area supply blend's distribution characteristics. The Cal Water distributes SFPUC and BAWSCA blended supply to the mid-Peninsula Belmont zone, producing the hard 176 mg/L.
At 176 mg/L, Belmont residents face regular hard water challenges. Monthly descaling and water softeners are recommended. California Water Service consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.
Geology & Source: Reservoir supply from the Hetch Hetchy and BAWSCA blend via the California Water Service (Mid-Peninsula) — the San Mateo County mid-Peninsula Belmont corridor (Sierra Nevada calcareous-poor granite — the calcareous-poor mid-Peninsula San Mateo County Bay Area supply; effective treatment); hard supply at 176 mg/L in San Mateo County.