Winnetka Water Hardness & Quality Report (2026)
Water Hardness
14.4 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
602.4 mg/L
Est. Daily Cost
$0.66
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 Winnetka, your appliances are currently losing 33% efficiency due to mineral buildup.
| Appliance | In Winnetka | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 4.5 yrs | 12 yrs | -63% |
| Water Heater | 5.8 yrs | 15 yrs | -61% |
Regional Water Comparison
How Winnetka compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Winnetka, Illinois | 246 mg/L | 8.6 ppt | 🔴 Very Hard | river |
| Wilmette, Illinois | 234.5 mg/L | 8.2 ppt | 🔴 Very Hard | river |
| Glenview, Illinois | 261.5 mg/L | 9.1 ppt | 🔴 Very Hard | river |
| Skokie, Illinois | 236.5 mg/L | 8.3 ppt | 🔴 Very Hard | river |
| Evanston, Illinois | 267 mg/L | 9.3 ppt | 🔴 Very Hard | river |
National Benchmark
How Winnetka compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Winnetka | 246 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Winnetka's Water Unique?
Local geology and source profile
Winnetka, Illinois, in Cook County — a Cook County village on the North Shore adjacent to Glencoe and Kenilworth on Lake Michigan in the north Chicago metro — receives its water from the City of Winnetka Water, drawing directly from Lake Michigan (Cook County) through the North Shore distribution.
The very hard 246 mg/L hardness and TDS of 602.4 mg/L reflect the Cook County North Shore Lake Michigan supply's very hard dolomitic character — among the hardest direct Lake Michigan withdrawals in the Chicago metro (compare Markham IL: 233/551 in south Cook on the Chicago DWM supply; Palos Heights IL: 152/280 in southwest Cook on the Illinois American Water blend; Winnetka harder as a direct North Shore Lake Michigan draw). The Lake Michigan at Cook County — Silurian Niagaran Dolomite (highly dolomitic — primary hardness contributor), Devonian carbonate shelf (calcareous — secondary contributor), and Quaternary Great Lakes glacial drift (calcareous — TDS contributor).
At 246 mg/L with TDS 602, Winnetka's water is very hard. A water softener is strongly recommended to prevent rapid scale buildup. A reverse osmosis system is advisable for drinking water. The PFAS level of 8.6 ppt warrants a certified drinking water filter — the Cook County north Chicago industrial corridor contribute to Winnetka's elevated readings.
Geology & Source: Winnetka in Cook County draws from the City of Winnetka Water on Lake Michigan (Cook County, north Shore Chicago metro, Illinois) — Lake Michigan at Cook County is developed in Silurian Niagaran Dolomite (highly dolomitic) and Devonian carbonate shelf (calcareous) — Illinois Cook County Lake Michigan Silurian-Devonian dolomitic North Shore supply produces very hard water at 246 mg/L with TDS 602.4 mg/L.