Hard water in St. Francis, WI
Reported by Milwaukee Waterworks · September 2025
- WI typical
- 170 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in St. Francis carries roughly 135 mg/L of dissolved calcium and magnesium, or 7.9 grains per gallon. That is hard water. The number comes from Milwaukee Waterworks, dated September 2025.
At 135 mg/L, St. Francis is 35 mg/L below the typical Wisconsin figure of 170. Of the 10 nearest cities we track, 3 have softer water and 4 have harder. The range nearby runs from 129 mg/L in Whitefish Bay to 210 in South Milwaukee.
What 135 mg/L means at home
Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.
Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.
Soap and detergent need a little more to lather, and soap scum shows up in the tub.
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 135 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 × 7.9 gpg = 1,775 grains a day. A 24,000-grain unit regenerates about every 13 days.
EPA record for St. Francis's water system
No health-based violations since 2016
Serves about 626,000 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
TapWaterData ties St. Francis to this system. EPA's service-area records do not name St. Francis, so check the utility printed on your water bill.
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 St. Francis water hard?
Yes. It measures about 135 mg/L (7.9 grains per gallon), which the USGS classes as hard.
What is the water hardness in St. Francis in grains per gallon?
About 7.9 gpg. One grain per gallon equals 17.1 mg/L, so 135 mg/L divided by 17.1 gives 7.9.
What size water softener do I need in St. Francis?
For 3 people using 75 gallons each per day, 7.9 gpg works out to about 1,775 grains a day. A 24,000-grain softener covers that with a regeneration about every 13 days.
Has the St. Francis water system had EPA violations?
EPA records show no health-based violations for Milwaukee Waterworks since 2016.
Nearby cities
- Cudahy142 mg/LHard
- South Milwaukee210 mg/LVery hard
- Oak Creek210 mg/LVery hard
- Greenfield135 mg/LHard
- Milwaukee135 mg/LHard
- West Allis135 mg/LHard
- Shorewood130 mg/LHard
- Franklin210 mg/LVery hard
- Whitefish Bay129 mg/LHard
- Wauwatosa134 mg/LHard
Hardness data: TapWaterData US Water Hardness (utility report, September 26, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.