Hard water in Flossmoor, IL
Reported by Flossmoor · October 2025
- IL typical
- 139 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
Tap water in Flossmoor has about 146 mg/L of hardness, which is 8.5 grains per gallon. On the USGS scale that counts as hard. The number comes from Flossmoor, dated October 2025.
At 146 mg/L, Flossmoor is close to the typical Illinois figure of 139 mg/L. Of the 10 nearest cities we track, 2 have softer water and 8 have harder. The range nearby runs from 112 mg/L in Homewood to 524 in Crete.
What 146 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 146 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 × 8.5 gpg = 1,921 grains a day. A 24,000-grain unit regenerates about every 12 days.
EPA record for Flossmoor's water system
No health-based violations since 2016
Serves about 9,371 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 3
- Open now
- 1
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 Flossmoor water hard?
Yes. It measures about 146 mg/L (8.5 grains per gallon), which the USGS classes as hard.
What is the water hardness in Flossmoor in grains per gallon?
About 8.5 gpg. One grain per gallon equals 17.1 mg/L, so 146 mg/L divided by 17.1 gives 8.5.
What size water softener do I need in Flossmoor?
For 3 people using 75 gallons each per day, 8.5 gpg works out to about 1,921 grains a day. A 24,000-grain softener covers that with a regeneration about every 12 days.
Has the Flossmoor water system had EPA violations?
EPA records show no health-based violations for Flossmoor since 2016. There were also 3 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Homewood112 mg/LModerately hard
- Chicago Heights229 mg/LVery hard
- Park Forest163 mg/LHard
- Richton Park206 mg/LVery hard
- South Holland140 mg/LHard
- Tinley Park300 mg/LVery hard
- Crete524 mg/LVery hard
- Dolton229 mg/LVery hard
- Blue Island229 mg/LVery hard
- Calumet City229 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (utility report, October 6, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.