Hard water in McHenry, IL
Reported by McHenry · April 2025
- IL typical
- 139 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 48k grain
- Data
- Utility report
McHenry water measures 384 mg/L (22.5 gpg) of hardness, very hard by USGS standards. The number comes from McHenry, dated April 2025.
At 384 mg/L, McHenry is 245 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 146 mg/L in Volo to 573 in Lake Barrington.
What 384 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 384 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 × 22.5 gpg = 5,054 grains a day. A 48,000-grain unit regenerates about every 9 days.
EPA record for McHenry's water system
No health-based violations since 2016
Serves about 22,335 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 23
- 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 McHenry water hard?
Yes. It measures about 384 mg/L (22.5 grains per gallon), which the USGS classes as very hard.
What is the water hardness in McHenry in grains per gallon?
About 22.5 gpg. One grain per gallon equals 17.1 mg/L, so 384 mg/L divided by 17.1 gives 22.5.
What size water softener do I need in McHenry?
For 3 people using 75 gallons each per day, 22.5 gpg works out to about 5,054 grains a day. A 48,000-grain softener covers that with a regeneration about every 9 days.
Has the McHenry water system had EPA violations?
EPA records show no health-based violations for McHenry since 2016. There were also 23 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Wonder Lake292 mg/LVery hard
- Johnsburg353 mg/LVery hard
- Lakemoor223 mg/LVery hard
- Volo146 mg/LHard
- Crystal Lake388 mg/LVery hard
- Woodstock343 mg/LVery hard
- Cary378 mg/LVery hard
- Wauconda146 mg/LHard
- Lake Barrington573 mg/LVery hard
- Lake in the Hills283 mg/LVery hard
Hardness data: TapWaterData US Water Hardness (utility report, April 21, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.