Duncan Water Hardness & Quality Report (2026)
Water Hardness
21.6 grains per gallon
Source
reservoir
pH Level
8.5
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
973.1 mg/L
Est. Daily Cost
$0.99
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 Duncan, your appliances are currently losing 45% efficiency due to mineral buildup.
| Appliance | In Duncan | 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 Duncan compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Duncan, Oklahoma | 370.5 mg/L | 6.4 ppt | 🔴 Very Hard | reservoir |
| Lawton, Oklahoma | 78 mg/L | 2.5 ppt | 🟡 Moderately Hard | reservoir |
| Chickasha, Oklahoma | 82 mg/L | 2.6 ppt | 🟡 Moderately Hard | reservoir |
| Wichita Falls, Texas | 408 mg/L | 11.7 ppt | 🔴 Very Hard | mixed |
| Ardmore, Oklahoma | 277.5 mg/L | 5.2 ppt | 🔴 Very Hard | reservoir |
National Benchmark
How Duncan compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Duncan | 370.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
Bring Badger-quality water to your Duncan home
Shop water softeners on Amazon.com →
What Makes Duncan's Water Unique?
Local geology and source profile
Duncan, Oklahoma, in Stephens County in south-central Oklahoma — the hometown of Halliburton and a historic oil patch and ranching community in the Anadarko Basin petroleum corridor — receives its municipal water from the City of Duncan Public Works, drawing from Lake Duncan and Fuqua Lake on the Washita River watershed in Stephens County. These reservoir impoundments collect runoff from south-central Oklahoma's rolling Permian Red Bed plain, one of the most mineral-rich terrestrial landscapes in the United States.
The extreme 370.5 mg/L hardness and near-1,000 TDS of 973.1 mg/L are among the most severe water quality challenges in the Oklahoma dataset, reflecting the Washita River watershed's dense Permian evaporite geology. South-central Oklahoma's surface and near-surface geology is dominated by the Permian Anadarko Basin's upper formations — including the Blaine Formation gypsum (calcium sulfate), Wellington Formation calcareous shale and limestone, and Permian Red Beds (alternating red sandstone, siltstone, and gypsum deposits). When rainfall drains through or over these Permian formations, it dissolves extraordinary amounts of calcium sulfate from gypsum beds, calcium carbonate from limestone layers, and magnesium from dolomitic beds — loading the Washita River with extreme mineral concentrations. Duncan's oil-patch heritage means the industrial landscape contributes additional mineral complexity.
At 370.5 mg/L, Duncan households face among Oklahoma's hardest water conditions. Scale forms within days on all heated water surfaces, dishwashers require water softener treatment, and the pronounced mineral taste of near-1,000 TDS water makes unfiltered tap water generally unpalatable for drinking. A whole-house water softener is a household necessity. Reverse osmosis for drinking water is the standard solution throughout south-central Oklahoma's Permian evaporite belt. The PFAS level of 6.4 ppt warrants a certified drinking water filter in addition to softener treatment — the Anadarko Basin oil and gas production corridor contributes to the regional PFAS baseline.
Geology & Source: Duncan in Stephens County draws from Lake Duncan or Fuqua Lake on the Washita River watershed — the Washita drains south-central Oklahoma's Permian Anadarko Basin over Permian Red Bed evaporites (gypsum, anhydrite), calcareous Wellington Formation, and Blaine Formation gypsite — intense evaporite and carbonate dissolution produces extreme hardness at 370.5 mg/L with near-1,000 TDS.