Hard water in Des Plaines, IL
Reported by Des Plaines · April 2025
- IL typical
- 139 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in Des Plaines carries roughly 126 mg/L of dissolved calcium and magnesium, or 7.4 grains per gallon. That is hard water. The number comes from Des Plaines, dated April 2025.
At 126 mg/L, Des Plaines is 13 mg/L below the typical Illinois figure of 139. Of the 10 nearest cities we track, 5 have softer water and 5 have harder. The range nearby runs from 104 mg/L in Schiller Park to 229 in Glenview.
What 126 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 126 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 × 7.4 gpg = 1,658 grains a day. A 24,000-grain unit regenerates about every 14 days.
EPA record for Des Plaines's water system
No health-based violations since 2016
Serves about 60,675 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 5
- Open now
- 3
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 Des Plaines water hard?
Yes. It measures about 126 mg/L (7.4 grains per gallon), which the USGS classes as hard.
What is the water hardness in Des Plaines in grains per gallon?
About 7.4 gpg. One grain per gallon equals 17.1 mg/L, so 126 mg/L divided by 17.1 gives 7.4.
What size water softener do I need in Des Plaines?
For 3 people using 75 gallons each per day, 7.4 gpg works out to about 1,658 grains a day. A 24,000-grain softener covers that with a regeneration about every 14 days.
Has the Des Plaines water system had EPA violations?
EPA records show no health-based violations for Des Plaines since 2016. There were also 5 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Mount Prospect112 mg/LModerately hard
- Elk Grove Village141 mg/LHard
- Glenview229 mg/LVery hard
- Schiller Park104 mg/LModerately hard
- Bensenville104 mg/LModerately hard
- Morton Grove229 mg/LVery hard
- Arlington Heights115 mg/LModerately hard
- Wheeling132 mg/LHard
- Franklin Park104 mg/LModerately hard
- Rolling Meadows229 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (utility report, April 22, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.