Oak Forest Water Hardness & Quality Report (2026)
Water Hardness
15.6 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
691.9 mg/L
Est. Daily Cost
$0.71
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 Oak Forest, your appliances are currently losing 36% efficiency due to mineral buildup.
| Appliance | In Oak Forest | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 3.7 yrs | 12 yrs | -69% |
| Water Heater | 5 yrs | 15 yrs | -67% |
Regional Water Comparison
How Oak Forest compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Oak Forest, Illinois | 267.5 mg/L | 9.3 ppt | 🔴 Very Hard | river |
| Midlothian, Illinois | 116.5 mg/L | 4.2 ppt | 🟡 Moderately Hard | river |
| Country Club Hills, Illinois | 273.5 mg/L | 9.5 ppt | 🔴 Very Hard | river |
| Markham, Illinois | 233 mg/L | 8.1 ppt | 🔴 Very Hard | river |
| Tinley Park, Illinois | 204 mg/L | 7.2 ppt | 🔴 Very Hard | river |
National Benchmark
How Oak Forest compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Oak Forest | 267.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Oak Forest's Water Unique?
Local geology and source profile
Oak Forest, Illinois, in Cook County — a major south Chicago suburban community (Oak Forest is a significant Cook County city — a south suburban Chicago community in the southwest Cook County cluster adjacent to Tinley Park and Orland Park; Oak Forest is home of Advocate Trinity Hospital (formerly Advocate Christ Medical Center Oak Forest) and the Oak Forest Health Center (one of the most significant Cook County public health facilities — Oak Forest has historically been home of a major Cook County health institution serving the south suburban population)), a diverse Cook County community with a primarily working-class to middle-class suburban family, Polish-American, and increasingly African-American population, adjacent to Tinley Park and Crestwood in the south Cook County corridor, home of the Oak Forest Metra Rock Island District station (one of the most important Rock Island Metra commuter rail connections to Chicago's Loop), and a south Chicago suburban community with a strong working-class character — draws its municipal water supply from Lake Michigan via the Illinois American Water Company. Water hardness in Oak Forest measures 267.5 mg/L — classified as very hard.
Oak Forest's very hard supply reflects the south Cook County Lake Michigan distribution zone's very limited softening. Illinois American Water distributes Lake Michigan supply to the south Cook County Oak Forest zone with very limited softening, producing the very hard 267.5 mg/L.
At 267.5 mg/L, Oak Forest residents face significant hard water challenges. Regular water softeners and descaling are strongly recommended. Illinois American Water consistently delivers water meeting all Illinois EPA and EPA Safe Drinking Water Act requirements.
Geology & Source: Lake supply from the Lake Michigan via the Illinois American Water Company (south Cook County) — the Cook County south Chicago suburban Oak Forest corridor (Silurian calcareous Niagaran Dolomite — the extremely calcareous south Cook County Chicago suburban dolomite with Lake Michigan supply; very limited softening); very hard supply at 267.5 mg/L in Cook County.