Darien Water Hardness & Quality Report (2026)
Water Hardness
7.5 grains per gallon
Source
river
pH Level
7.7
neutral = 7.0
Lead
0.002 mg/L
✓ Below action level
TDS
216.6 mg/L
Est. Daily Cost
$0.34
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 Darien, your appliances are currently losing 17% efficiency due to mineral buildup.
| Appliance | In Darien | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 5.4 yrs | 8.5 yrs | -36% |
| Washing Machine | 8.8 yrs | 12 yrs | -27% |
| Water Heater | 10.5 yrs | 15 yrs | -30% |
Regional Water Comparison
How Darien compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Darien, Illinois | 128.5 mg/L | 4.6 ppt | 🟠 Hard | river |
| Westmont, Illinois | 197 mg/L | 6.9 ppt | 🔴 Very Hard | river |
| Hinsdale, Illinois | 229 mg/L | 8 ppt | 🔴 Very Hard | river |
| Downers Grove, Illinois | 176.5 mg/L | 6.2 ppt | 🟠 Hard | river |
| Woodridge, Illinois | 260.5 mg/L | 9.1 ppt | 🔴 Very Hard | river |
National Benchmark
How Darien compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Darien | 128.5 mg/L | 🟠 Moderate |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
Bring Badger-quality water to your Darien home
Shop water softeners on Amazon.com →
What Makes Darien's Water Unique?
Local geology and source profile
Darien, Illinois, in DuPage County — a well-established southwestern DuPage County suburb along I-55 between Downers Grove and Bolingbrook — receives its municipal water from the DuPage Water Commission (DWC) or through Illinois American Water, which supplies Lake Michigan water via the Chicago-area regional transmission network to the DuPage County suburbs. The DuPage Water Commission purchases treated Lake Michigan water from the City of Chicago and delivers it through the western suburban DuPage distribution system.
The moderately hard 128.5 mg/L hardness and TDS of 216.6 mg/L reflect the DuPage Water Commission Lake Michigan supply after treatment and distribution to the southwestern DuPage suburbs. Lake Michigan raw water carries moderate carbonate hardness from its drainage basin (the Silurian Niagara Dolomite and Devonian limestone Great Lakes basin), typically ~130–160 mg/L at intake. The DWC supply for DuPage County's southwestern communities at Darien reflects the Lake Michigan baseline well, as the Lake Shore to DuPage transmission system is relatively modern and maintains consistent finished water quality. The moderately hard reading is typical for the DuPage County Lake Michigan supply zone.
At 128.5 mg/L, Darien's water is moderately hard — a comfortable and manageable household supply for the southwestern DuPage suburbs. Scale builds in kettles and coffee machines over months, dishwashers benefit from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling of heating appliances is appropriate. The PFAS level of 4.6 ppt warrants a certified drinking water filter — the DuPage County suburban corridor, the I-55 and I-355 transportation corridor's industrial parks, and the Lake Michigan tributary industrial discharge from the broader Chicago metropolitan area contribute to the DuPage Water Commission supply PFAS background.
Geology & Source: Darien in DuPage County draws from the DuPage Water Commission or Illinois American Water supplying Lake Michigan water via the Chicago regional transmission system — Lake Michigan receives carbonate drainage from the Silurian Niagara Dolomite Great Lakes basin — Lake Michigan carbonate input and treatment produce moderately hard water at 128.5 mg/L with TDS 217 mg/L in this southwestern DuPage County suburb.