Duarte Water Hardness & Quality Report (2026)
Water Hardness
180+ mg/L
Very Hardestimated · not lab-verified
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
$0.91
energy & soap waste
Source: See methodology section below · 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 45% efficiency due to mineral buildup.
| Appliance | In Duarte | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 4.7 yrs | 8.5 yrs | -45% |
| Washing Machine | 6.6 yrs | 12 yrs | -45% |
| Water Heater | 8.3 yrs | 15 yrs | -45% |
Regional Water Comparison
How Duarte compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Duarte, California | ≈ 180+ mg/L | 4.6 ppt | 🔴 Very Hard | mixed |
| Monrovia, California | ≈ 120–179 mg/L | 62.5 ppt | 🟠 Hard | groundwater |
| Baldwin Park, California | ≈ 180+ mg/L | 0 ppt | 🔴 Very Hard | groundwater |
| Arcadia, California | ≈ 180+ mg/L | 29.2 ppt | 🔴 Very Hard | groundwater |
| Vincent, California | ≈ 120–179 mg/L | 6.8 ppt | 🟠 Hard | mixed |
National Benchmark
How Duarte compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Duarte | ≈ 180+ mg/L | 🔴 High |
| USA National Avg | 151 mg/L | 🟠 Moderate |
| Scarsdale Top Rated | 0.02 mg/L | 🟢 None |
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What Makes Duarte's Water Unique?
Local geology and source profile
Cal-Am Water Company - Duarte (operated by American Water) serves Duarte, Bradbury, portions of Azusa, Irwindale, Monrovia, and unincorporated Los Angeles County areas. The utility draws entirely from groundwater wells in the Main San Gabriel Basin; no surface reservoirs or rivers are used. Treatment occurs at wellheads with chlorine disinfection (hypochlorite) to maintain bacteriological quality; no filtration or fluoridation is applied. The utility is based at 8657 Grand Avenue, Rosemead, CA 91770 (contact: 626-614-2533).
The Main San Gabriel Basin occupies the Pomona Valley portion of the San Gabriel River watershed in Los Angeles County. Water infiltrates through alluvial fan deposits from the San Gabriel Mountains, interacting with Quaternary sediments — sands, gravels, and silts — derived from granitic and metamorphic bedrock of the Peninsular Ranges Batholith upstream. Dissolution of mineral ions from limestone-bearing alluvium and basin fill produces a very hard supply with elevated dissolved solids typical of regional groundwater.
Very hard water promotes significant limescale buildup in pipes, water heaters, dishwashers, washing machines, and fixtures, reducing efficiency and lifespan. Soap scum forms readily, requiring more detergent for cleaning. Maintenance includes regular vinegar descaling, installing sediment pre-filters, and flushing water heaters annually; a water softener is strongly recommended to prevent scaling and extend equipment life. The 2024 CCR confirms compliance with all EPA standards across 250+ constituents; naturally occurring fluoride averages 0.33 ppm with no added fluoridation; bacteriological quality is maintained via chlorination.
Geology & Source: Main San Gabriel Basin — Quaternary alluvial sands and gravels from Mesozoic Peninsular Ranges Batholith granitic and metamorphic bedrock; calcium and magnesium dissolve from limestone-bearing sediments, producing very hard groundwater
Other California Water Reports
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Frequently Asked Questions
Is Duarte's water safe to drink?
Do I need a water softener in Duarte?
How does Duarte compare to the USA average?
Data Sources & Methodology
Water quality data for Duarte is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.
Water Hardness
Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.
pH
Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.
TDS — Total Dissolved Solids
Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.
PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances
EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.
Lead
Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.
Appliance Lifespan
Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.