Arlington Heights Water Hardness & Quality Report (2026)
Water Hardness
15.2 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
664.4 mg/L
Est. Daily Cost
$0.70
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 Arlington Heights, your appliances are currently losing 35% efficiency due to mineral buildup.
| Appliance | In Arlington Heights | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 3.9 yrs | 12 yrs | -68% |
| Water Heater | 5.2 yrs | 15 yrs | -65% |
Regional Water Comparison
How Arlington Heights compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Arlington Heights, Illinois | 261 mg/L | 9.1 ppt | 🔴 Very Hard | river |
| Rolling Meadows, Illinois | 167.5 mg/L | 5.9 ppt | 🟠 Hard | river |
| Prospect Heights, Illinois | 268.5 mg/L | 9.3 ppt | 🔴 Very Hard | river |
| Mount Prospect, Illinois | 177 mg/L | 6.2 ppt | 🟠 Hard | river |
| Palatine, Illinois | 148.5 mg/L | 5.3 ppt | 🟠 Hard | river |
National Benchmark
How Arlington Heights compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Arlington Heights | 261 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Arlington Heights's Water Unique?
Local geology and source profile
Arlington Heights, Illinois, in northwest Cook County (one of Chicago's largest and most affluent northwest suburbs, home of Arlington Park racetrack) draws its municipal water supply from Lake Michigan via the Northwest Water Commission and City of Chicago Department of Water Management (DWM) wholesale distribution, treated and distributed by the Village of Arlington Heights Water Division through the northwest Cook County suburban water network. Water hardness in Arlington Heights measures 261 mg/L — classified as very hard, substantially above Chicago proper's distribution areas.
Arlington Heights' very high hardness (261 mg/L) on Lake Michigan source water — well above Chicago's citywide range (100–210 mg/L) — reflects the northwest suburban Cook County distribution infrastructure's extensive mineral accumulation from the Lake Michigan source. The Northwest Water Commission distribution system serves the densely developed northwest Cook County suburbs through a network that includes long transmission mains running through areas overlying the Silurian Niagaran Dolomite at shallow depth beneath the Des Plaines River Valley. The transmission distance from Chicago's water treatment plants (Jardine WPP), combined with the northwest suburban distribution network's older cast-iron main sections and possible local mixing in the Northwest Water Commission infrastructure, produces the very high hardness at Arlington Heights taps.
At 261 mg/L, Arlington Heights residents face significant hard water challenges. Scale deposits form rapidly on faucet aerators, showerheads, shower glass, and tile — monthly descaling with citric acid solution is essential maintenance. Dishwashers require rinse-aid, and water heaters need annual inspection. Northwest Water Commission and Chicago DWM consistently deliver water meeting all Illinois EPA and federal EPA Safe Drinking Water Act requirements.
Geology & Source: Lake supply from Lake Michigan via the Northwest Water Commission and City of Chicago Department of Water Management (DWM) wholesale — the Cook County northwest suburban Lake Michigan distribution zone; very hard supply at 261 mg/L — significantly harder than Chicago proper — reflecting the northwest suburban Cook County distribution network mineral accumulation.