Janesville Water Hardness & Quality Report (2026)
Water Hardness
20.4 grains per gallon
Source
groundwater
pH Level
8.5
neutral = 7.0
Lead
0.008 mg/L
✓ Below action level
TDS
68 mg/L
Est. Daily Cost
$0.93
energy & soap waste
Source: See methodology section below · 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 Janesville, your appliances are currently losing 45% efficiency due to mineral buildup.
| Appliance | In Janesville | 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 Janesville compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Janesville, Wisconsin | 350 mg/L | 0 ppt | 🔴 Very Hard | groundwater |
| Beloit, Wisconsin | 346 mg/L | 3 ppt | 🔴 Very Hard | groundwater |
| Roscoe, Illinois | ≈ 120–179 mg/L | 6.1 ppt | 🟠 Hard | groundwater |
| Fort Atkinson, Wisconsin | ≈ 180+ mg/L | 0 ppt | 🔴 Very Hard | groundwater |
| Stoughton, Wisconsin | 308.16 mg/L | 7.1 ppt | 🔴 Very Hard | groundwater |
National Benchmark
How Janesville compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Janesville | 350 mg/L | 🔴 High |
| USA National Avg | 151 mg/L | 🟠 Moderate |
| Scarsdale Top Rated | 0.02 mg/L | 🟢 None |
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What Makes Janesville's Water Unique?
Local geology and source profile
Janesville Water Utility serves approximately 64,415 residents in Janesville, Wisconsin, within Rock County. The utility operates seven wells with a total capacity of up to 29 million gallons per day, drawing exclusively from the preglacial Rock River Valley aquifer system more than 100 feet underground. There are no surface water treatment plants; supply comes solely from these deep groundwater wells without reliance on the nearby Rock River.
The supply originates from the preglacial Rock River Valley aquifer, shaped by Pleistocene glacial deposits overlying Paleozoic bedrock including limestone and dolomite formations common in southern Wisconsin. These unconsolidated sand and gravel layers dissolve minerals from the underlying carbonate rocks over millennia, resulting in a very hard supply rich in naturally occurring calcium and magnesium bicarbonates.
At 350 mg/L, this is very hard water that causes significant scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and increasing energy costs. Dry skin, soap scum, and spotted dishes are common. A water softener is strongly recommended to prevent clogs, extend appliance life, and improve lathering. Third-party analyses note potential contaminants including m-Xylene, lead, TTHMs, and PFAS exceeding EPA health guidelines though within legal limits; point-of-use filtration is advised.
Geology & Source: Preglacial Rock River Valley glacial outwash aquifer; Pleistocene sand and gravel over Paleozoic limestone and dolomite bedrock — calcium and magnesium dissolution produces very hard groundwater
Other Wisconsin Water Reports
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Frequently Asked Questions
Is Janesville's water safe to drink?
Do I need a water softener in Janesville?
How does Janesville compare to the USA average?
Data Sources & Methodology
Water quality data for Janesville is derived from geographic and geological modelling of the surrounding region. No federal monitoring station data was available for this location.
Water Hardness
Modelled estimate based on state-level USGS geological survey data for this region. No direct USGS Water Quality Portal measurement was matched to this city — the value reflects a statistical range calibrated to the state's dominant rock types and typical source water characteristics.
pH
Estimated from regional geology and source water characteristics. pH is correlated with water hardness and local bedrock — values may differ from utility-reported figures.
TDS — Total Dissolved Solids
Estimated using a derived ratio from water hardness and regional conductance profiles. TDS in natural water correlates strongly with total mineral content including hardness ions.
PFAS — Perfluoroalkyl and Polyfluoroalkyl Substances
EPA UCMR5 (5th Unregulated Contaminant Monitoring Rule, 2023–2025) — sum of PFAS compounds detected at the public water system serving this city. A value of 0 indicates the system was sampled with no detection above reporting limits.
Lead
Modelled estimate based on the EPA Lead and Copper Rule 90th-percentile tap-sample methodology. No publicly available per-city lead dataset with sufficient national coverage exists. Values are a conservative baseline derived from city population tier and infrastructure age — all estimates are maintained below the EPA action level of 0.015 mg/L.
Appliance Lifespan
Calculated from water hardness using a linear degradation model. Baseline lifespans represent soft-water performance (kettle: 8.5 yrs, washing machine: 12.0 yrs, water heater: 15.0 yrs). Hard water mineral scale progressively reduces operational life in direct proportion to hardness concentration.