Hard water in Janesville, WI
Reported by Janesville Water Utility · October 2025
- WI typical
- 170 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 32k grain
- Data
- Utility report
Tap water in Janesville has about 298 mg/L of hardness, which is 17.4 grains per gallon. On the USGS scale that counts as very hard. The number comes from Janesville Water Utility, dated October 2025. Reports for this system disagree, with values from 298 to 350 mg/L.
Janesville sits 128 mg/L above the typical Wisconsin figure of 170. Of the 10 nearest cities we track, 5 have softer water and 5 have harder. The range nearby runs from 88 mg/L in Elkhorn to 360 in Delavan.
What 298 mg/L means at home
Scale forms fast here. Kettles and coffee makers need regular descaling, and showerheads clog unless you clean them.
Tank water heaters collect mineral sediment that insulates the water from the burner, so flushing the tank matters more than usual.
Dishes and glass shower doors spot easily. Soap scum and a dull film on hair or laundry are common complaints.
Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.
What to do about it
At 298 mg/L most of the trouble is scale, and only a few things deal with it.
Ion-exchange water softener
The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.
Salt-free conditioner
No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.
Reverse osmosis or carbon filter
Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.
3 people × 75 gallons a day × 17.4 gpg = 3,922 grains a day. A 32,000-grain unit regenerates about every 8 days.
EPA record for Janesville's water system
No health-based violations since 2016
Serves about 64,415 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 1
- Open now
- 0
Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.
Questions
Is Janesville water hard?
Yes. It measures about 298 mg/L (17.4 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Janesville in grains per gallon?
About 17.4 gpg. One grain per gallon equals 17.1 mg/L, so 298 mg/L divided by 17.1 gives 17.4.
What size water softener do I need in Janesville?
For 3 people using 75 gallons each per day, 17.4 gpg works out to about 3,922 grains a day. A 32,000-grain softener covers that with a regeneration about every 8 days.
Has the Janesville water system had EPA violations?
EPA records show no health-based violations for Janesville Water Utility since 2016. There were also 1 monitoring or reporting violation, which are about late or missing tests and notices.
Nearby cities
- Milton342 mg/LVery hard
- Edgerton291 mg/LVery hard
- Beloit333 mg/LVery hard
- Whitewater323 mg/LVery hard
- Fort Atkinson278 mg/LVery hard
- Stoughton312 mg/LVery hard
- Delavan360 mg/LVery hard
- Elkhorn88 mg/LModerately hard
- Jefferson280 mg/LVery hard
- Oregon283 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (utility report, October 1, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.