San Anselmo Water Hardness & Quality Report (2026)
Water Hardness
9 grains per gallon
Source
mixed
pH Level
8.1
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
449 mg/L
Est. Daily Cost
$0.41
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 San Anselmo, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In San Anselmo | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 4.5 yrs | 8.5 yrs | -47% |
| Washing Machine | 7.9 yrs | 12 yrs | -34% |
| Water Heater | 9.5 yrs | 15 yrs | -37% |
Regional Water Comparison
How San Anselmo compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ San Anselmo, California | 153.5 mg/L | 6.5 ppt | 🟠 Hard | mixed |
| San Rafael, California | 49.5 mg/L | 3.5 ppt | 🟢 Soft | mixed |
| Larkspur, California | 109 mg/L | 5.2 ppt | 🟡 Moderately Hard | mixed |
| Mill Valley, California | 126 mg/L | 5.7 ppt | 🟠 Hard | mixed |
| Novato, California | 110.5 mg/L | 5.3 ppt | 🟡 Moderately Hard | mixed |
National Benchmark
How San Anselmo compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ San Anselmo | 153.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes San Anselmo's Water Unique?
Local geology and source profile
San Anselmo, California, in Marin County — a Marin County town adjacent to San Rafael and Fairfax in the north San Francisco Bay — receives its water from the Marin Municipal Water District, drawing from Lagunitas Creek or Alpine Lake (Marin County) through the north San Francisco Bay distribution.
The hard 153.5 mg/L hardness and TDS of 449 mg/L are notably harder than other Bay Area supplies (EBMUD: ~35 mg/L; SFPUC: ~40 mg/L) — the Marin County Lagunitas-Alpine watershed intersects the Jurassic Coast Range Ophiolite's ultramafic calcareous formations, producing significantly elevated hardness and TDS over the typical California coastal supply (compare El Sobrante CA EBMUD: 35/72; San Anselmo MMWD dramatically harder from the Marin ophiolite contact). The Lagunitas-Alpine watershed at Marin County — Jurassic Coast Range Ophiolite (slightly calcareous — primary hardness contributor from ultramafic dissolution), Cretaceous Franciscan Complex (insoluble — dilutant), and Quaternary Marin Valley alluvium (calcareous — TDS contributor).
At 153.5 mg/L with TDS 449, San Anselmo's water is hard. A water softener is recommended to prevent scale buildup. A reverse osmosis system is advisable for drinking water. The PFAS level of 6.5 ppt warrants a certified drinking water filter — the Marin County north San Francisco Bay industrial corridor contribute to San Anselmo's elevated readings.
Geology & Source: San Anselmo in Marin County draws from the Marin Municipal Water District on Lagunitas Creek or Alpine Lake (Marin County, north San Francisco Bay, California) — the Lagunitas-Alpine watershed drains Cretaceous Franciscan Complex (insoluble) and Jurassic Coast Range Ophiolite (slightly calcareous) — California Marin County MMWD Lagunitas Cretaceous-Jurassic Franciscan supply produces hard water at 153.5 mg/L with TDS 449 mg/L.