How hard is the water in Mokena, IL?

Tap water hardness
91mg/L
5.3gpg
Moderately hard

Reported by Mokena · July 2024

IL typical
139 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

Tap water in Mokena has about 91 mg/L of hardness, which is 5.3 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Mokena, dated July 2024.

Mokena on the hardness scale, with nearby cities
060120180240300360+IL typical 139New Lenox: 137 mg/LNew Lenox 137Flossmoor: 146 mg/LFlossmoor 146Orland Hills: 147 mg/LOrland Hills 147Orland Park: 147 mg/LOrland Park 147Richton Park: 206 mg/LRichton Park 206Frankfort: 287 mg/LFrankfort 287Homer Glen: 287 mg/LHomer Glen 287Tinley Park: 300 mg/LTinley Park 300Lockport: 458 mg/LLockport 458Manhattan: 372 mg/LManhattan 372Mokena 91mg/L as calcium carbonate060120180240300360+IL 139New Lenox: 137 mg/LNew Lenox 137Orland Hills: 147 mg/LOrland Hil. 147Orland Park: 147 mg/LOrland Park 147Frankfort: 287 mg/LFrankfort 287Homer Glen: 287 mg/LHomer Glen 287Tinley Park: 300 mg/LTinley Park 30091 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

At 91 mg/L, Mokena is 48 mg/L below the typical Illinois figure of 139. None of the 10 nearest cities we track has softer water. The range nearby runs from 137 mg/L in New Lenox to 458 in Lockport.

What 91 mg/L means at home

You may see faint white spots on glasses and shower doors after the water dries.

Scale builds up slowly. A kettle or coffee maker needs descaling now and then, maybe every few months.

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

Optional. Plenty of households at this level live with it and descale the kettle now and then.

Water softener

Worth a look if spots on glass bother you, or if your tankless water heater manual asks for softer water.

Carbon filter

Improves taste and removes chlorine. It leaves calcium and magnesium in place.

Softener size for Mokena

3 people × 75 gallons a day × 5.3 gpg = 1,199 grains a day. A 24,000-grain unit regenerates about every 20 days.

Size it for your household

EPA record for Mokena's water system

Mokena · PWSID IL1970600

No health-based violations since 2016

Serves about 19,887 people from surface water.

Health-based
0
Monitoring or reporting
5
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 Mokena water hard?

Somewhat. It measures about 91 mg/L (5.3 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Mokena in grains per gallon?

About 5.3 gpg. One grain per gallon equals 17.1 mg/L, so 91 mg/L divided by 17.1 gives 5.3.

What size water softener do I need in Mokena?

For 3 people using 75 gallons each per day, 5.3 gpg works out to about 1,199 grains a day. A 24,000-grain softener covers that with a regeneration about every 20 days.

Has the Mokena water system had EPA violations?

EPA records show no health-based violations for Mokena since 2016. There were also 5 monitoring or reporting violations, which are about late or missing tests and notices.

Nearby cities

All 192 cities in Illinois

Hardness data: TapWaterData US Water Hardness (utility report, July 6, 2024), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.