Hard water in Clarendon Hills, IL
Reported by Clarendon Hills · July 2025
- IL typical
- 139 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
Clarendon Hills water measures 159 mg/L (9.3 gpg) of hardness, hard by USGS standards. The number comes from Clarendon Hills, dated July 2025. Reports for this system disagree, with values from 159 to 400 mg/L.
Clarendon Hills sits 20 mg/L above the typical Illinois figure of 139. Of the 10 nearest cities we track, 8 have softer water and 2 have harder. The range nearby runs from 99 mg/L in Villa Park to 287 in Darien.
What 159 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 159 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 × 9.3 gpg = 2,095 grains a day. A 24,000-grain unit regenerates about every 11 days.
EPA record for Clarendon Hills's water system
No health-based violations since 2016
Serves about 8,702 people from surface water.
- Health-based
- 0
- Monitoring or reporting
- 3
- 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 Clarendon Hills water hard?
Yes. It measures about 159 mg/L (9.3 grains per gallon), which the USGS classes as hard.
What is the water hardness in Clarendon Hills in grains per gallon?
About 9.3 gpg. One grain per gallon equals 17.1 mg/L, so 159 mg/L divided by 17.1 gives 9.3.
What size water softener do I need in Clarendon Hills?
For 3 people using 75 gallons each per day, 9.3 gpg works out to about 2,095 grains a day. A 24,000-grain softener covers that with a regeneration about every 11 days.
Has the Clarendon Hills water system had EPA violations?
EPA records show no health-based violations for Clarendon Hills since 2016. There were also 3 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Westmont127 mg/LHard
- Hinsdale133 mg/LHard
- Downers Grove131 mg/LHard
- Darien287 mg/LVery hard
- La Grange122 mg/LHard
- La Grange Park129 mg/LHard
- Lombard287 mg/LVery hard
- Villa Park99 mg/LModerately hard
- Woodridge134 mg/LHard
- Berkeley104 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (utility report, July 9, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.