Stillwater Water Hardness & Quality Report (2026)
Water Hardness
12.8 grains per gallon
Source
reservoir
pH Level
8.3
neutral = 7.0
Lead
0.005 mg/L
✓ Below action level
TDS
450.3 mg/L
Est. Daily Cost
$0.59
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 Stillwater, your appliances are currently losing 29% efficiency due to mineral buildup.
| Appliance | In Stillwater | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 2.4 yrs | 8.5 yrs | -72% |
| Washing Machine | 5.5 yrs | 12 yrs | -54% |
| Water Heater | 6.8 yrs | 15 yrs | -55% |
Regional Water Comparison
How Stillwater compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Stillwater, Oklahoma | 219.5 mg/L | 4.4 ppt | 🔴 Very Hard | reservoir |
| Ponca City, Oklahoma | 367.5 mg/L | 6.4 ppt | 🔴 Very Hard | reservoir |
| Edmond, Oklahoma | 98 mg/L | 2.8 ppt | 🟡 Moderately Hard | reservoir |
| Midwest City, Oklahoma | 326 mg/L | 5.8 ppt | 🔴 Very Hard | reservoir |
| Del City, Oklahoma | 315 mg/L | 5.7 ppt | 🔴 Very Hard | reservoir |
National Benchmark
How Stillwater compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Stillwater | 219.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Stillwater's Water Unique?
Local geology and source profile
Stillwater, Oklahoma, the Payne County seat — home of Oklahoma State University (OSU — a major Big 12 university), a quintessential college town on the Oklahoma prairie, known for Gallagher-Iba Arena, the OSU cowboy football program, and the National Wrestling Hall of Fame — draws its municipal water supply from Lake Carl Blackwell (Cimarron River tributary) via the City of Stillwater Utilities Water Division. Water hardness in Stillwater measures 219.5 mg/L — classified as very hard.
Stillwater's very hard supply reflects the north-central Oklahoma watershed's Permian calcareous and evaporitic geology. The Lake Carl Blackwell watershed (Boomer Creek and Camp Lena Creek drainage) drains: the Permian Garber Sandstone (calcareous-cemented sandstone of the Oklahoma Permian red bed sequence); the Permian Wellington Formation (calcareous mudstone, silty red beds, and minor evaporite — salt and gypsum dissolution contributing dissolved calcium and sulfate); and the Permian Chase Group calcareous limestone (marine limestone of the Oklahoma Permian sequence, highly calcareous). The Permian calcareous and evaporitic terrain produces the very hard 219.5 mg/L at Stillwater.
At 219.5 mg/L, Stillwater residents face significant hard water challenges. Scale deposits form rapidly on all fixtures and tile — monthly descaling with citric acid solution is essential maintenance. City of Stillwater Utilities Water Division consistently delivers water meeting all Oklahoma DEQ and EPA Safe Drinking Water Act requirements.
Geology & Source: River supply from the Lake Carl Blackwell (Cimarron River tributary) and the Stillwater Creek sub-basin via the City of Stillwater Utilities Water Division — the Payne County north-central Oklahoma (Permian Garber Sandstone and Wellington Formation calcareous red beds and evaporite terrain); very hard supply at 219.5 mg/L in Payne County.