Eureka Water Hardness & Quality Report (2026)
Water Hardness
16.7 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
763.5 mg/L
Est. Daily Cost
$0.76
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 Eureka, your appliances are currently losing 38% efficiency due to mineral buildup.
| Appliance | In Eureka | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 3 yrs | 12 yrs | -75% |
| Water Heater | 5 yrs | 15 yrs | -67% |
Regional Water Comparison
How Eureka compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Eureka, Missouri | 285.5 mg/L | 8.4 ppt | 🔴 Very Hard | river |
| Wildwood, Missouri | 118.5 mg/L | 4.1 ppt | 🟡 Moderately Hard | river |
| Ballwin, Missouri | 87.5 mg/L | 3.3 ppt | 🟡 Moderately Hard | river |
| Manchester, Missouri | 137 mg/L | 4.6 ppt | 🟠 Hard | river |
| Chesterfield, Missouri | 107.5 mg/L | 3.9 ppt | 🟡 Moderately Hard | river |
National Benchmark
How Eureka compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Eureka | 285.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Eureka's Water Unique?
Local geology and source profile
Eureka, Missouri, in Saint Louis County — a Saint Louis County city adjacent to Pacific and Wildwood on the Meramec River at the Gateway Arch gateway in east Missouri — receives its water from Missouri American Water, drawing from the Meramec River through the east-central Missouri distribution.
The very hard 285.5 mg/L hardness and high TDS of 763.5 mg/L reflect the Saint Louis County Meramec supply's very hard Ozark character — the Ordovician Gasconade Dolomite and Mississippian Burlington Formation are highly calcareous-dolomitic formations in the Missouri Ozark Plateau, and the Meramec River acquires substantial dissolved mineral content from its karst Ozark drainage (compare Pacific MO: 280/750 in Franklin County comparable; Wildwood MO: 289/777 in Saint Louis County comparable; Eureka consistent very hard from the same Saint Louis County Meramec River Ordovician calcareous supply). The Meramec watershed — Ordovician Gasconade Dolomite (highly calcareous — primary hardness contributor), Mississippian Burlington Formation (calcareous — secondary contributor), and Quaternary Meramec River alluvium (calcareous — TDS contributor).
At 285.5 mg/L with TDS 764, Eureka's water is very hard — a water softener is strongly recommended to protect plumbing and appliances. The PFAS level of 8.4 ppt warrants a certified drinking water filter. Review Missouri American Water's annual water quality report.
Geology & Source: Eureka in Saint Louis County draws from the Missouri American Water on the Meramec River (Saint Louis County, east Missouri) — the Meramec watershed at Ozark Plateau draws from Ordovician Gasconade Dolomite (highly calcareous) and Mississippian Burlington Formation (calcareous) — Missouri Saint Louis County Meramec River Ordovician calcareous supply produces very hard water at 285.5 mg/L with TDS 763.5 mg/L.