San Dimas 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
540.5 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 San Dimas, your appliances are currently losing 24% efficiency due to mineral buildup.
| Appliance | In San Dimas | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.8 yrs | 8.5 yrs | -55% |
| Washing Machine | 7.1 yrs | 12 yrs | -41% |
| Water Heater | 8.5 yrs | 15 yrs | -43% |
Regional Water Comparison
How San Dimas compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ San Dimas, California | 177 mg/L | 7 ppt | 🟠 Hard | mixed |
| La Verne, California | 52.5 mg/L | 3.4 ppt | 🟢 Soft | mixed |
| Glendora, California | 129 mg/L | 5.6 ppt | 🟠 Hard | mixed |
| Pomona, California | 178 mg/L | 7.1 ppt | 🟠 Hard | mixed |
| Diamond Bar, California | 185 mg/L | 7.3 ppt | 🔴 Very Hard | mixed |
National Benchmark
How San Dimas compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ San Dimas | 177 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 Dimas's Water Unique?
Local geology and source profile
San Dimas, California, in Los Angeles County — a major east San Gabriel Valley community (San Dimas is in the east San Gabriel Valley at the base of the San Gabriel Mountains, adjacent to La Verne and Pomona), home of the original Raging Waters water park (one of the largest water parks in Southern California — a major Southern California summer recreation destination adjacent to San Dimas), home of Bonita Unified School District (one of the recognized school districts in the San Gabriel Valley), a diverse Los Angeles County community with a significant Latino-American and Asian-American population, and a community in the historic Citrus Belt of the east San Gabriel Valley (San Dimas was a major citrus growing community in the early 20th century) — draws its municipal water supply via the Three Valleys Municipal Water District. Water hardness in San Dimas measures 177 mg/L — classified as hard.
San Dimas's hard supply reflects the east San Gabriel Valley's calcareous geology and MWD Colorado River blend dominance. The San Gabriel River watershed and MWD import at San Dimas–east LA County draws from: the San Gabriel Mountains alluvial fan (calcareous-moderate Quaternary alluvium); and the MWD Colorado River supply (approximately 280–320 mg/L — the calcareous Colorado River Plateau–Rocky Mountain dissolved minerals). Three Valleys MWD's Colorado River-dominated blend produces the hard 177 mg/L.
At 177 mg/L, San Dimas residents face regular hard water challenges. Monthly descaling with citric acid solution is recommended. Three Valleys Municipal Water District consistently delivers water meeting all California State Water Board and EPA Safe Drinking Water Act requirements.
Geology & Source: Mountain reservoir supply from the San Gabriel River (San Gabriel Reservoir watershed) and Metropolitan Water District (MWD) import via the Three Valleys Municipal Water District or Walnut Valley Water District — the Los Angeles County east San Gabriel Valley (Quaternary calcareous-moderate San Gabriel Mountains alluvium and MWD Colorado River/SWP blend; east San Gabriel Valley distribution); hard supply at 177 mg/L in Los Angeles County.