Oswego Water Hardness & Quality Report (2026)
Water Hardness
7.8 grains per gallon
Source
river
pH Level
7.8
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
228.3 mg/L
Est. Daily Cost
$0.35
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 Oswego, your appliances are currently losing 18% efficiency due to mineral buildup.
| Appliance | In Oswego | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.2 yrs | 8.5 yrs | -39% |
| Washing Machine | 8.7 yrs | 12 yrs | -28% |
| Water Heater | 10.3 yrs | 15 yrs | -31% |
Regional Water Comparison
How Oswego compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Oswego, Illinois | 133 mg/L | 4.8 ppt | 🟠 Hard | river |
| Montgomery, Illinois | 143.5 mg/L | 5.1 ppt | 🟠 Hard | river |
| Aurora, Illinois | 279.5 mg/L | 9.7 ppt | 🔴 Very Hard | river |
| Yorkville, Illinois | 275 mg/L | 9.6 ppt | 🔴 Very Hard | river |
| North Aurora, Illinois | 234 mg/L | 8.2 ppt | 🔴 Very Hard | river |
National Benchmark
How Oswego compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Oswego | 133 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Oswego's Water Unique?
Local geology and source profile
Oswego, Illinois, in Kendall County — a major west suburban Chicago community (Oswego is one of the most dramatically fast-growing Illinois communities — Kendall County as a whole has been among the fastest-growing counties in Illinois for consecutive decades; Oswego grew from approximately 13,000 in 2000 to over 35,000 by the mid-2020s), a primarily residential community in the Fox River Valley (the Fox River runs through Oswego — the Fox River Valley west of Chicago is a historically significant recreational and residential corridor), a diverse Kendall County community with a significant Latino-American and young family population, and part of the I-88 west suburban Chicago growth corridor — draws its municipal water supply from the Lake Michigan–Fox River blend via the City of Oswego Water Division. Water hardness in Oswego measures 133 mg/L — classified as moderately hard.
Oswego's moderate hardness reflects the Kendall County Fox River Valley supply blend's characteristics. The Fox River watershed at Oswego–Kendall County draws from: the Silurian Niagaran Dolomite (highly calcareous dolomite of the Illinois–Wisconsin border zone); and the Wisconsin Age calcareous glacial drift (carbonate-rich till of the Kendall County plain). The blend with Lake Michigan supply in the DuPage distribution zone produces the moderate 133 mg/L.
At 133 mg/L, Oswego residents encounter moderate scale accumulation. Monthly cleaning with citric acid solution is recommended. City of Oswego Water Division consistently delivers water meeting all Illinois EPA and federal EPA Safe Drinking Water Act requirements.
Geology & Source: Lake supply from Lake Michigan via the DuPage Water Commission or Fox Metro Water Reclamation District (Fox River supply blend) — the Kendall County west Illinois Fox River Valley (Lake Michigan calcareous-moderate freshwater supply blend with Silurian Niagaran Dolomite Fox River watershed contributions — the Kendall County west suburban supply; Oswego distribution); moderately hard supply at 133 mg/L in Kendall County.