Redwood Shores Water Hardness & Quality Report (2026)
Water Hardness
10.8 grains per gallon
Source
mixed
pH Level
8.3
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
580.7 mg/L
Est. Daily Cost
$0.49
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 Redwood Shores, your appliances are currently losing 25% efficiency due to mineral buildup.
| Appliance | In Redwood Shores | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.5 yrs | 8.5 yrs | -59% |
| Washing Machine | 6.8 yrs | 12 yrs | -43% |
| Water Heater | 8.2 yrs | 15 yrs | -45% |
Regional Water Comparison
How Redwood Shores compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Redwood Shores, California | 184.5 mg/L | 7.4 ppt | 🔴 Very Hard | mixed |
| San Carlos, California | 163 mg/L | 6.8 ppt | 🟠 Hard | mixed |
| Belmont, California | 176 mg/L | 7.1 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 |
National Benchmark
How Redwood Shores compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Redwood Shores | 184.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Redwood Shores's Water Unique?
Local geology and source profile
Redwood Shores, California, in San Mateo County — a San Mateo County planned community adjacent to Foster City and San Carlos on the San Francisco Bay shoreline — receives its water from California Water Service, drawing from a blend of Hetch Hetchy/SFPUC imported water and local groundwater through the San Francisco Peninsula distribution.
The hard 184.5 mg/L hardness and high TDS of 580.7 mg/L reflect the San Mateo County supply's hard blended character — while Hetch Hetchy delivers very soft Sierra Nevada water, the local groundwater component from the Santa Clara Formation and Bay margin alluvium is hard and saline; Redwood Shores' bay-front location means the groundwater blend skews toward higher hardness and TDS than inland Peninsula communities (compare Foster City CA: 179/561 in San Mateo County comparable; San Carlos CA: 188/600 in San Mateo County comparable; Redwood Shores consistent hard from the same San Mateo County SFPUC blended Precambrian supply). The Peninsula blended supply — Precambrian Franciscan Complex (insoluble — primary dilutant), Cretaceous Santa Clara Formation (slightly calcareous — hardness contributor), and Quaternary Bay margin alluvium (saline calcareous — TDS contributor).
At 184.5 mg/L with TDS 581, Redwood Shores' water is hard — scale builds in appliances. Quarterly descaling is appropriate. The PFAS level of 7.4 ppt warrants a certified drinking water filter. Review California Water Service's annual water quality report.
Geology & Source: Redwood Shores in San Mateo County draws from the California Water Service on the Hetch Hetchy/SFPUC and local blended supply (San Mateo County, San Francisco Peninsula) — the Peninsula supply draws from Precambrian Franciscan Complex (insoluble) and Cretaceous Santa Clara Formation (slightly calcareous) — California San Mateo County SFPUC blended Precambrian supply produces hard water at 184.5 mg/L with TDS 580.7 mg/L.