Hard water in Onalaska, WI

Tap water hardness
337mg/L
19.7gpg
Very hard

Reported by Onalaska Waterworks · August 2022

WI typical
170 mg/L
EPA health violations since 2016
0
Softener for 3 people
32k grain
Data
Utility report

Onalaska water measures 337 mg/L (19.7 gpg) of hardness, very hard by USGS standards. The number comes from Onalaska Waterworks, dated August 2022.

Onalaska on the hardness scale, with nearby cities
060120180240300360+WI typical 170Chippewa Falls: 49 mg/LChippewa Falls 49Lake Hallie: 61 mg/LLake Hallie 61Wisconsin Rapids: 62 mg/LWisconsin Rapids 62Eau Claire: 101 mg/LEau Claire 101Altoona: 102 mg/LAltoona 102Reedsburg: 162 mg/LReedsburg 162West Salem: 244 mg/LWest Salem 244Marshfield: 249 mg/LMarshfield 249La Crosse: 290 mg/LLa Crosse 290Holmen: 319 mg/LHolmen 319Onalaska 337mg/L as calcium carbonate060120180240300360+WI 170Eau Claire: 101 mg/LEau Claire 101Altoona: 102 mg/LAltoona 102Reedsburg: 162 mg/LReedsburg 162West Salem: 244 mg/LWest Salem 244La Crosse: 290 mg/LLa Crosse 290Holmen: 319 mg/LHolmen 319337 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Onalaska sits 167 mg/L above the typical Wisconsin figure of 170. None of the 10 nearest cities we track has harder water. The range nearby runs from 49 mg/L in Chippewa Falls to 319 in Holmen.

What 337 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 337 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.

Softener size for Onalaska

3 people × 75 gallons a day × 19.7 gpg = 4,435 grains a day. A 32,000-grain unit regenerates about every 7 days.

Size it for your household

EPA record for Onalaska's water system

Onalaska Waterworks · PWSID WI6320327

No health-based violations since 2016

Serves about 18,000 people from groundwater.

Health-based
0
Monitoring or reporting
0
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 Onalaska water hard?

Yes. It measures about 337 mg/L (19.7 grains per gallon), which the USGS classes as very hard.

What is the water hardness in Onalaska in grains per gallon?

About 19.7 gpg. One grain per gallon equals 17.1 mg/L, so 337 mg/L divided by 17.1 gives 19.7.

What size water softener do I need in Onalaska?

For 3 people using 75 gallons each per day, 19.7 gpg works out to about 4,435 grains a day. A 32,000-grain softener covers that with a regeneration about every 7 days.

Has the Onalaska water system had EPA violations?

EPA records show no health-based violations for Onalaska Waterworks since 2016.

Nearby cities

All 112 cities in Wisconsin

Hardness data: TapWaterData US Water Hardness (utility report, August 15, 2022), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.