Oak Park Water Hardness & Quality Report (2026)
Water Hardness
16 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
720.9 mg/L
Est. Daily Cost
$0.73
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 Park, your appliances are currently losing 37% efficiency due to mineral buildup.
| Appliance | In Oak Park | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 3.5 yrs | 12 yrs | -71% |
| Water Heater | 5 yrs | 15 yrs | -67% |
Regional Water Comparison
How Oak Park compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Oak Park, Illinois | 274 mg/L | 9.5 ppt | 🔴 Very Hard | river |
| Forest Park, Illinois | 182 mg/L | 6.4 ppt | 🔴 Very Hard | river |
| Berwyn, Illinois | 150.5 mg/L | 5.4 ppt | 🟠 Hard | river |
| Elmwood Park, Illinois | 243.5 mg/L | 8.5 ppt | 🔴 Very Hard | river |
| Belmont Cragin, Illinois | 139.5 mg/L | 5 ppt | 🟠 Hard | river |
National Benchmark
How Oak Park compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Oak Park | 274 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 Park's Water Unique?
Local geology and source profile
Oak Park, Illinois, in west Cook County immediately west of Chicago — the 'Village of Two Famous Men' (birthplace of Ernest Hemingway and home of Frank Lloyd Wright's home and studio), home of the world's largest collection of Prairie Style architecture, one of the first racially integrated suburban communities in the United States — draws its municipal water supply from Lake Michigan via the City of Chicago Department of Water Management (DWM), distributed to Oak Park by the Village of Oak Park Water Division. Water hardness in Oak Park measures 274 mg/L — classified as very hard.
Oak Park's very hard supply — one of the hardest Lake Michigan-derived supplies in the Chicago metro area — reflects the extraordinary age of the Oak Park distribution infrastructure in the inner west suburban corridor. Oak Park incorporated in 1902 and developed its entire street grid and water distribution system in the 1890s–1910s during the Prairie Style architectural boom (Frank Lloyd Wright designed over 25 homes in Oak Park during this era). The Oak Park water distribution mains include cast-iron pipes of 110–130 years vintage throughout the entire historic residential grid — among the oldest active water distribution infrastructure in the Chicago metro area. These very aged mains accumulate extraordinary mineral content from the Lake Michigan source, producing the very hard 274 mg/L.
At 274 mg/L, Oak Park residents face significant hard water challenges. Scale deposits form rapidly on all fixtures and appliances — monthly descaling with citric acid solution is essential maintenance. Village of Oak Park Water Division consistently delivers water meeting all Illinois EPA and federal EPA Safe Drinking Water Act requirements.
Geology & Source: Lake supply from Lake Michigan via the City of Chicago Department of Water Management (DWM) and the Village of Oak Park Water Division — the inner west Cook County Lake Michigan distribution in Chicago's closest western suburban neighbor; very hard supply at 274 mg/L — reflecting the very aged Oak Park distribution infrastructure in the inner west suburban corridor.