Walnut Water Hardness & Quality Report (2026)
Water Hardness
8.9 grains per gallon
Source
mixed
pH Level
8
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
434.7 mg/L
Est. Daily Cost
$0.40
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 Walnut, your appliances are currently losing 20% efficiency due to mineral buildup.
| Appliance | In Walnut | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 4.6 yrs | 8.5 yrs | -46% |
| Washing Machine | 8 yrs | 12 yrs | -33% |
| Water Heater | 9.5 yrs | 15 yrs | -37% |
Regional Water Comparison
How Walnut compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Walnut, California | 151.5 mg/L | 6.3 ppt | 🟠 Hard | mixed |
| South San Jose Hills, California | 58.5 mg/L | 3.6 ppt | 🟢 Soft | mixed |
| Diamond Bar, California | 185 mg/L | 7.3 ppt | 🔴 Very Hard | mixed |
| Rowland Heights, California | 165 mg/L | 6.7 ppt | 🟠 Hard | mixed |
| Covina, California | 170 mg/L | 6.8 ppt | 🟠 Hard | mixed |
National Benchmark
How Walnut compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Walnut | 151.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Walnut's Water Unique?
Local geology and source profile
Walnut, California, in Los Angeles County — a major east San Gabriel Valley community (Walnut is a significant Los Angeles County city in the eastern San Gabriel Valley — an east LA County incorporated community known for its planned residential neighborhoods, Tier-1 public schools (Walnut Unified School District is consistently among the highest-performing school districts in California — a significant draw for Chinese-American and other Asian-American families prioritizing education), and large home sizes relative to closer-in Los Angeles suburbs), a diverse Los Angeles County community with a predominantly Chinese-American and other Asian-American population (Walnut has one of the highest percentages of Asian-American residents of any city in Los Angeles County, reflecting the eastern San Gabriel Valley's transformation into one of the most significant concentrations of Chinese-American communities in the United States), home of Mount San Antonio College (Mt. SAC — one of the largest community colleges in the United States by enrollment), and one of the east San Gabriel Valley's most desirable communities — draws its municipal water supply via the Walnut Valley Water District. Water hardness in Walnut measures 151.5 mg/L — classified as moderately hard.
Walnut's moderate hardness reflects the east San Gabriel Valley alluvial basin supply blend characteristics. The Walnut Valley Water District distributes MWD import and San Gabriel Valley groundwater supply to the east LA County Walnut zone, producing the moderate 151.5 mg/L.
At 151.5 mg/L, Walnut residents encounter moderate scale accumulation. Monthly cleaning is recommended. Walnut Valley Water District consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.
Geology & Source: Imported supply from the San Gabriel River (Puente Hills Basin groundwater) via the Walnut Valley Water District (Metropolitan Water District blend) — the Los Angeles County east San Gabriel Valley Walnut corridor (Quaternary calcareous-moderate San Gabriel Valley alluvium — the calcareous east Los Angeles County San Gabriel Valley alluvial basin; limited softening); moderately hard supply at 151.5 mg/L in Los Angeles County.