Sun Prairie Water Hardness & Quality Report (2026)
Water Hardness
11.5 grains per gallon
Source
groundwater
pH Level
8.2
neutral = 7.0
Lead
0.006 mg/L
✓ Below action level
TDS
570.1 mg/L
Est. Daily Cost
$0.52
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 Sun Prairie, your appliances are currently losing 26% efficiency due to mineral buildup.
| Appliance | In Sun Prairie | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 3.1 yrs | 8.5 yrs | -64% |
| Washing Machine | 6.3 yrs | 12 yrs | -48% |
| Water Heater | 7.7 yrs | 15 yrs | -49% |
Regional Water Comparison
How Sun Prairie compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Sun Prairie, Wisconsin | 196.5 mg/L | 5.3 ppt | 🔴 Very Hard | groundwater |
| Madison, Wisconsin | 145.5 mg/L | 4.2 ppt | 🟠 Hard | groundwater |
| Waunakee, Wisconsin | 233.5 mg/L | 6.2 ppt | 🔴 Very Hard | groundwater |
| Stoughton, Wisconsin | 178.5 mg/L | 4.9 ppt | 🟠 Hard | groundwater |
| Middleton, Wisconsin | 252.5 mg/L | 6.6 ppt | 🔴 Very Hard | groundwater |
National Benchmark
How Sun Prairie compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Sun Prairie | 196.5 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Sun Prairie's Water Unique?
Local geology and source profile
Sun Prairie, Wisconsin, in Dane County — a major east Dane County suburban community (Sun Prairie is one of the most rapidly growing cities in Dane County — a significant east Madison suburb in the US-151 corridor, with one of the fastest growth rates in Wisconsin over the past two decades driven by Madison metro suburban expansion), home of the Sun Prairie community that produced Georgia O'Keeffe (the great American modernist painter was born in Sun Prairie in 1887 — a notable artistic heritage for the Wisconsin prairie community), a diverse Dane County community with a significant working-class, professional, and growing Hispanic-American population, and a rapidly developing east Dane County community adjacent to the Madison–Dane County metro — draws its municipal water supply from the Silurian Dolomite aquifer via the City of Sun Prairie Water Division. Water hardness in Sun Prairie measures 196.5 mg/L — classified as very hard.
Sun Prairie's very hard supply reflects the east Dane County Silurian dolomite aquifer's highly calcareous character. The Niagaran and Galena Dolomite aquifer at Sun Prairie–Dane County draws from the Silurian Niagaran Dolomite (highly calcareous dolomite of the Great Lakes region Paleozoic Platform — the same formation that forms the Niagara Falls escarpment). City of Sun Prairie applies limited treatment, producing the very hard 196.5 mg/L.
At 196.5 mg/L, Sun Prairie residents face significant hard water challenges. Regular water softeners and appliance descaling are strongly recommended. City of Sun Prairie Water Division consistently delivers water meeting all Wisconsin DNR and EPA Safe Drinking Water Act requirements.
Geology & Source: Groundwater from the Silurian Dolomite aquifer (Niagaran Dolomite) via the City of Sun Prairie Water Division — the Dane County east Wisconsin Dane County corridor (Silurian calcareous Niagaran Dolomite and Ordovician calcareous Galena Group Dolomite — the highly calcareous east Wisconsin Great Lakes Paleozoic dolomite shelf; Dane County dolomite aquifer at Sun Prairie); very hard supply at 196.5 mg/L in Dane County.