Hard water in De Pere, WI
County estimate from 172 water samples in Brown County · July 2026
- WI typical
- 170 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- County estimate
Water samples from around De Pere put hardness at about 194 mg/L (11.3 gpg), which would be very hard on the USGS scale. Treat this as a rough guide: it is the median of 172 samples taken across Brown County, mostly wells and streams, not a test of De Pere's treated tap water. One more reason for caution: EPA lists De Pere's water system as using surface water, which is often softer than the wells behind the county figure.
At 194 mg/L, De Pere is 24 mg/L above the typical Wisconsin figure of 170. Of the 10 nearest cities we track, 9 have softer water and 1 has harder. The range nearby runs from 67 mg/L in Neenah to 196 in Suamico.
What 194 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 194 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 × 11.3 gpg = 2,554 grains a day. A 24,000-grain unit regenerates about every 9 days.
EPA record for De Pere's water system
No health-based violations since 2016
Serves about 25,660 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
EPA lists this system as serving De Pere.
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 De Pere water hard?
Yes. It measures about 194 mg/L (11.3 grains per gallon), which the USGS classes as very hard.
What is the water hardness in De Pere in grains per gallon?
About 11.3 gpg. One grain per gallon equals 17.1 mg/L, so 194 mg/L divided by 17.1 gives 11.3.
What size water softener do I need in De Pere?
For 3 people using 75 gallons each per day, 11.3 gpg works out to about 2,554 grains a day. A 24,000-grain softener covers that with a regeneration about every 9 days.
Has the De Pere water system had EPA violations?
EPA records show no health-based violations for De Pere Waterworks Sa 1 since 2016.
Nearby cities
- Allouez136 mg/LHard
- Green Bay137 mg/LHard
- Suamico196 mg/LVery hard
- Little Chute87 mg/LModerately hard
- Kimberly73 mg/LModerately hard
- Appleton81 mg/LModerately hard
- Menasha166 mg/LHard
- Fox Crossing166 mg/LHard
- Greenville152 mg/LHard
- Neenah67 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (county estimate, July 4, 2026), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.