Cahokia Water Hardness & Quality Report (2026)
Water Hardness
11.3 grains per gallon
Source
river
pH Level
8.2
neutral = 7.0
Lead
0.005 mg/L
✓ Below action level
TDS
409.8 mg/L
Est. Daily Cost
$0.52
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 Cahokia, your appliances are currently losing 26% efficiency due to mineral buildup.
| Appliance | In Cahokia | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.2 yrs | 8.5 yrs | -62% |
| Washing Machine | 6.4 yrs | 12 yrs | -47% |
| Water Heater | 7.8 yrs | 15 yrs | -48% |
Regional Water Comparison
How Cahokia compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Cahokia, Illinois | 194 mg/L | 6.8 ppt | 🔴 Very Hard | river |
| St. Louis, Missouri | 123 mg/L | 4.3 ppt | 🟠 Hard | river |
| East Saint Louis, Illinois | 196.5 mg/L | 6.9 ppt | 🔴 Very Hard | river |
| Lemay, Missouri | 183.5 mg/L | 5.8 ppt | 🔴 Very Hard | river |
| Granite City, Illinois | 164.5 mg/L | 5.8 ppt | 🟠 Hard | river |
National Benchmark
How Cahokia compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Cahokia | 194 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Cahokia's Water Unique?
Local geology and source profile
Cahokia, Illinois, in Saint Clair County — a Saint Clair County village adjacent to East St. Louis and Belleville in southwest Illinois across from St. Louis — receives its water from Illinois American Water, drawing from the Mississippi River (Saint Clair County) through the southwest Illinois distribution.
The hard 194 mg/L hardness and TDS of 409.8 mg/L reflect the southwest Illinois Mississippi River supply's hard Ozark-Missouri calcareous character — consistent with other southwest Illinois Saint Clair County Mississippi River communities. The Mississippi River at Saint Clair County receives the Missouri River (calcareous — primary hardness contributor from the Great Plains carbonate input), Ohio River calcareous input, and Ozark Plateau drainage — Mississippian Burlington Limestone (calcareous), Ordovician St. Peter Sandstone (near-insoluble), and Devonian calcareous formations.
At 194 mg/L, Cahokia's water is hard — scale builds steadily in kettles and appliances, dishwashers benefit from rinse aid, and water heaters should be descaled annually. Monthly descaling is recommended. The PFAS level of 6.8 ppt warrants a certified drinking water filter — Scott Air Force Base (Saint Clair County — AFFF, directly in the Cahokia PFAS corridor) and the southwest Illinois East St. Louis industrial corridor contribute to Cahokia's readings.
Geology & Source: Cahokia in Saint Clair County draws from the Illinois American Water on the Mississippi River (Saint Clair County, southwest Illinois) — the Mississippi at Saint Clair County drains the Ozark Plateau (Ordovician St. Peter Sandstone — insoluble, Mississippian Burlington Limestone — calcareous) and the Missouri River calcareous input — Illinois Saint Clair County Mississippi River Ozark-Missouri calcareous watershed produces hard water at 194 mg/L with TDS 409.8 mg/L.