Oconomowoc Water Hardness & Quality Report (2026)
Water Hardness
15.1 grains per gallon
Source
groundwater
pH Level
8.5
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
846.2 mg/L
Est. Daily Cost
$0.69
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 Oconomowoc, your appliances are currently losing 34% efficiency due to mineral buildup.
| Appliance | In Oconomowoc | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 4 yrs | 12 yrs | -67% |
| Water Heater | 5.3 yrs | 15 yrs | -65% |
Regional Water Comparison
How Oconomowoc compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Oconomowoc, Wisconsin | 258.5 mg/L | 6.7 ppt | 🔴 Very Hard | groundwater |
| Hartford, Wisconsin | 93.5 mg/L | 3 ppt | 🟡 Moderately Hard | groundwater |
| Watertown, Wisconsin | 228 mg/L | 6 ppt | 🔴 Very Hard | groundwater |
| Waukesha, Wisconsin | 231.5 mg/L | 6.1 ppt | 🔴 Very Hard | groundwater |
| Whitewater, Wisconsin | 100 mg/L | 3.1 ppt | 🟡 Moderately Hard | groundwater |
National Benchmark
How Oconomowoc compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Oconomowoc | 258.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Oconomowoc's Water Unique?
Local geology and source profile
Oconomowoc, Wisconsin, in Waukesha County — a Waukesha County city adjacent to Delafield and Hartland in the southeast Wisconsin lake district — receives its municipal water from the Oconomowoc Water Division, drawing from local groundwater wells in the Waukesha County deep carbonate aquifer (southeast Wisconsin).
The very hard 258.5 mg/L hardness and very high TDS of 846.2 mg/L reflect the southeast Wisconsin deep Niagara Dolomite aquifer's intense carbonate character — among the hardest groundwater in the upper Midwest, consistent with other Waukesha County communities (Waukesha: 400+ mg/L from the deep Cambrian-Ordovician system). The Waukesha County aquifer is developed in Silurian Niagara Dolomite (very high purity dolomite bedrock — 95%+ calcium-magnesium carbonate), Ordovician Prairie du Chien Group dolomite, and Cambrian Jordan Sandstone. The near-pure Niagara Dolomite bedrock dissolves steadily into groundwater, producing the very hard southeast Wisconsin carbonate supply. Note: Waukesha County also has naturally occurring radium in deeper aquifer zones requiring specialized treatment.
At 258.5 mg/L with TDS 846, Oconomowoc's water is very hard. A water softener is strongly recommended. Scale builds rapidly on all surfaces, appliance lifespans are significantly shortened, and water heaters require annual descaling without softening. The PFAS level of 6.7 ppt warrants a certified drinking water filter — the Waukesha County southeast Wisconsin industrial corridor and the regional PFAS background contribute to Oconomowoc's readings.
Geology & Source: Oconomowoc in Waukesha County draws from local wells (Waukesha County, southeast Wisconsin) — the Waukesha County aquifer is developed in Silurian Niagara Dolomite (very high purity carbonate, highly soluble) and Ordovician Prairie du Chien dolomite bedrock — Wisconsin Waukesha County Silurian Niagara Dolomite bedrock aquifer produces very hard water at 258.5 mg/L with TDS 846.2 mg/L in this Waukesha County Wisconsin city.