Duarte Water Hardness & Quality Report (2026)
Water Hardness
5.5 grains per gallon
Source
mixed
pH Level
7.6
neutral = 7.0
Lead
0.004 mg/L
✓ Below action level
TDS
230.3 mg/L
Est. Daily Cost
$0.25
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 Duarte, your appliances are currently losing 13% efficiency due to mineral buildup.
| Appliance | In Duarte | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 6.5 yrs | 8.5 yrs | -24% |
| Washing Machine | 10.1 yrs | 12 yrs | -16% |
| Water Heater | 11.8 yrs | 15 yrs | -21% |
Regional Water Comparison
How Duarte compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Duarte, California | 94 mg/L | 4.6 ppt | 🟡 Moderately Hard | mixed |
| Monrovia, California | 34 mg/L | 2.9 ppt | 🟢 Soft | mixed |
| Baldwin Park, California | 80 mg/L | 4.2 ppt | 🟡 Moderately Hard | mixed |
| Arcadia, California | 156 mg/L | 6.4 ppt | 🟠 Hard | mixed |
| Vincent, California | 167.5 mg/L | 6.8 ppt | 🟠 Hard | mixed |
National Benchmark
How Duarte compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Duarte | 94 mg/L | 🟡 Low |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Duarte's Water Unique?
Local geology and source profile
Duarte, California, in Los Angeles County in the eastern San Gabriel Valley — a San Gabriel Valley foothill community adjacent to Monrovia, home to the City of Hope comprehensive cancer research and treatment center, at the foot of the San Gabriel Mountains — receives its municipal water from California American Water (CalAm) or the San Gabriel Valley Municipal Water District (SGVMWD), which draws from Metropolitan Water District of Southern California (MWD) imported supply and local San Gabriel Basin groundwater. Duarte's supply reflects the eastern San Gabriel Valley's blended water system.
The moderately soft 94 mg/L hardness and TDS of 230.3 mg/L are softer than many San Gabriel Valley communities, reflecting Duarte's position at the eastern San Gabriel Valley foothills where MWD-dominated supply with a significant State Water Project (SWP) soft component blends with local San Gabriel Basin alluvial groundwater. The SWP Feather River water (soft Sierra Nevada granite origin) provides a consistent soft-water dilution to the MWD blend at this eastern valley location, moderating the harder Colorado River component. The San Gabriel Basin groundwater from Raymond Basin and Main San Gabriel Basin alluvial fans at the mountain front contributes moderate dissolved minerals from granitic and metamorphic alluvial sediments.
At 94 mg/L, Duarte's water is moderately soft — one of the softer readings in the eastern San Gabriel Valley. Scale forms slowly over many months, soap lathers well, and the dishwasher produces clean results. Semi-annual descaling of heating appliances is adequate. The PFAS level of 4.6 ppt is moderate for LA County — the eastern San Gabriel Valley Superfund zone (historically contaminated by aerospace and defense contractors at locations like the Puente Hills area) and the Monrovia-Duarte corridor's industrial park network contribute to the local PFAS background.
Geology & Source: Duarte in Los Angeles County is served by California American Water (CalAm) or the San Gabriel Valley Municipal Water District drawing from Metropolitan Water District (MWD) import and the San Gabriel Basin groundwater — the eastern San Gabriel Basin alluvial aquifer and MWD blended supply produces moderately soft water at 94 mg/L with TDS 230 mg/L in this eastern San Gabriel Valley foothill community near the Monrovia foothills.