Oskaloosa Water Hardness & Quality Report (2026)
Water Hardness
17.6 grains per gallon
Source
river
pH Level
8.5
neutral = 7.0
Lead
0.007 mg/L
✓ Below action level
TDS
707 mg/L
Est. Daily Cost
$0.80
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 Oskaloosa, your appliances are currently losing 40% efficiency due to mineral buildup.
| Appliance | In Oskaloosa | 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 Oskaloosa compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Oskaloosa, Iowa | 300.5 mg/L | 6.2 ppt | 🔴 Very Hard | river |
| Pella, Iowa | 363 mg/L | 7.5 ppt | 🔴 Very Hard | river |
| Ottumwa, Iowa | 313.5 mg/L | 6.5 ppt | 🔴 Very Hard | river |
| Newton, Iowa | 176.5 mg/L | 3.7 ppt | 🟠 Hard | river |
| Marshalltown, Iowa | 180.5 mg/L | 3.8 ppt | 🔴 Very Hard | river |
National Benchmark
How Oskaloosa compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Oskaloosa | 300.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Oskaloosa's Water Unique?
Local geology and source profile
Oskaloosa, Iowa, in Mahaska County — a Mahaska County city adjacent to Ottumwa and Newton on the Des Moines River plateau in south-central Iowa — receives its water from the City of Oskaloosa Water Department, drawing from Lake Oskaloosa through the south-central Iowa distribution.
The very hard 300.5 mg/L hardness and high TDS of 707 mg/L reflect the Mahaska County Lake Oskaloosa supply's very hard calcareous character — the Pennsylvanian Desmoinesian limestone and Mississippian Burlington-Keokuk Limestone are among the most calcareous formations in Iowa, producing water hardness values among the highest in the state (compare Ottumwa IA: 295/694 in Wapello County comparable; Newton IA: 305/720 in Jasper County comparable; Oskaloosa consistent very hard from the same Mahaska County Lake Oskaloosa Pennsylvanian calcareous supply). The Des Moines River basin — Pennsylvanian Desmoinesian limestone (calcareous — primary hardness contributor), Mississippian Burlington-Keokuk Limestone (calcareous — secondary contributor), and Quaternary glacial drift (calcareous — TDS contributor).
At 300.5 mg/L with TDS 707, Oskaloosa's water is very hard — a water softener is strongly recommended to protect plumbing and appliances. Quarterly descaling is appropriate. The PFAS level of 6.2 ppt warrants a certified drinking water filter. Review the City of Oskaloosa's annual water quality report for the latest contaminant data.
Geology & Source: Oskaloosa in Mahaska County draws from the Oskaloosa Water on Lake Oskaloosa (Mahaska County, south-central Iowa) — the Des Moines watershed drains Pennsylvanian Desmoinesian limestone (calcareous) and Mississippian Burlington-Keokuk Limestone (calcareous) — Iowa Mahaska County Lake Oskaloosa Pennsylvanian calcareous supply produces very hard water at 300.5 mg/L with TDS 707 mg/L.