O'Fallon Water Hardness & Quality Report (2026)
Water Hardness
14 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
576.7 mg/L
Est. Daily Cost
$0.64
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 O'Fallon, your appliances are currently losing 32% efficiency due to mineral buildup.
| Appliance | In O'Fallon | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.7 yrs | 8.5 yrs | -80% |
| Washing Machine | 4.7 yrs | 12 yrs | -61% |
| Water Heater | 6 yrs | 15 yrs | -60% |
Regional Water Comparison
How O'Fallon compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ O'Fallon, Illinois | 239.5 mg/L | 8.4 ppt | 🔴 Very Hard | river |
| Shiloh, Illinois | 155.5 mg/L | 5.5 ppt | 🟠 Hard | river |
| Fairview Heights, Illinois | 236 mg/L | 8.2 ppt | 🔴 Very Hard | river |
| Swansea, Illinois | 234 mg/L | 8.2 ppt | 🔴 Very Hard | river |
| Belleville, Illinois | 111.5 mg/L | 4 ppt | 🟡 Moderately Hard | river |
National Benchmark
How O'Fallon compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ O'Fallon | 239.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes O'Fallon's Water Unique?
Local geology and source profile
O'Fallon, Illinois, in St. Clair County — a major south Illinois Metro East growing community (O'Fallon is a significant St. Clair County city — one of the fastest-growing cities in the Metro East (southern Illinois St. Louis suburban area); O'Fallon has grown dramatically since the 1990s as one of the most desirable St. Clair County suburbs adjacent to Scott Air Force Base (Scott AFB is one of the most important US Air Force command and logistics installations — home of the Air Mobility Command and the 375th Air Mobility Wing; Scott AFB is the largest employer in the Illinois Metro East area)), home of the O'Fallon Park system (one of the most extensive municipal park systems in the Illinois Metro East area), a diverse St. Clair County community with a significant military and veteran, professional, and middle-class suburban population, adjacent to Belleville in the south St. Clair County corridor, and one of the most rapidly growing Metro East suburban communities — draws its municipal water supply via the City of O'Fallon Water Division. Water hardness in O'Fallon measures 239.5 mg/L — classified as very hard.
O'Fallon's very hard supply reflects the south Illinois St. Clair County Mississippian limestone karst's calcareous character. The St. Clair County aquifer at O'Fallon draws from the Mississippian St. Louis and Ste. Genevieve Limestones (calcareous karst). City of O'Fallon applies limited softening, producing the very hard 239.5 mg/L.
At 239.5 mg/L, O'Fallon residents face significant hard water challenges. Regular water softeners and descaling are strongly recommended. City of O'Fallon Water Division consistently delivers water meeting all Illinois EPA and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Pennsylvanian Coal Measures aquifer and Mississippi River alluvial wells via the City of O'Fallon Water Division — the St. Clair County south Illinois Metro East O'Fallon corridor (Mississippian calcareous St. Louis and Ste. Genevieve Limestones — the calcareous south Illinois St. Clair County Metro East Mississippian karst; limited softening); very hard supply at 239.5 mg/L in St. Clair County.