Northbrook Water Hardness & Quality Report (2026)
Water Hardness
14.7 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
622.4 mg/L
Est. Daily Cost
$0.67
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 Northbrook, your appliances are currently losing 33% efficiency due to mineral buildup.
| Appliance | In Northbrook | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 4.3 yrs | 12 yrs | -64% |
| Water Heater | 5.6 yrs | 15 yrs | -63% |
Regional Water Comparison
How Northbrook compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Northbrook, Illinois | 251 mg/L | 8.7 ppt | 🔴 Very Hard | river |
| Deerfield, Illinois | 144 mg/L | 5.1 ppt | 🟠 Hard | river |
| Highland Park, Illinois | 219.5 mg/L | 7.7 ppt | 🔴 Very Hard | river |
| Glenview, Illinois | 261.5 mg/L | 9.1 ppt | 🔴 Very Hard | river |
| Winnetka, Illinois | 246 mg/L | 8.6 ppt | 🔴 Very Hard | river |
National Benchmark
How Northbrook compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Northbrook | 251 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Northbrook's Water Unique?
Local geology and source profile
Northbrook, Illinois, in Cook County — a major north Cook County suburb (Northbrook is one of the premier north suburban Chicago communities — an affluent north Cook County community adjacent to Glenview and Wilmette, with a strong commercial and light industrial base along the I-294 and Skokie Valley corridor), home of Allstate Insurance headquarters (a Fortune 100 company and one of the largest insurance companies in the United States — Allstate's corporate campus is a major economic anchor for Northbrook), a diverse Cook County community with a significant Jewish-American, South Asian-American, and Korean-American professional population, and a community known for excellent public schools and high quality of life — draws its municipal water supply from Lake Michigan via the North Shore Water Commission. Water hardness in Northbrook measures 251 mg/L — classified as very hard.
Northbrook's very hard supply — much harder than Chicago's own delivery — reflects the north suburban Cook County distribution characteristics. The North Shore Water Commission purchases wholesale Lake Michigan water from Chicago (raw hardness approximately 140–160 mg/L) and distributes through north Cook County (Glenview, Wilmette, Northbrook). The additional pipeline length and older north suburban mains (1940s–1960s residential development mains in the Northbrook area) produce the very hard 251 mg/L.
At 251 mg/L, Northbrook residents face severe hard water challenges. Weekly descaling and appliance protection measures are strongly recommended. North Shore Water Commission consistently delivers water meeting all Illinois EPA and federal EPA Safe Drinking Water Act requirements.
Geology & Source: Lake supply from Lake Michigan via the North Shore Water Commission (NSWC) — the Cook County north suburban Chicago Northbrook corridor (Lake Michigan calcareous-moderate freshwater supply — North Shore Water Commission treatment and distribution to Northbrook north Cook County zone; with distribution hardness accumulation); very hard supply at 251 mg/L in Cook County.