How hard is the water in Iowa City, IA?

Tap water hardness
76mg/L
4.4gpg
Moderately hard

Reported by Iowa City Water Department · August 2025

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

The water in Iowa City carries roughly 76 mg/L of dissolved calcium and magnesium, or 4.4 grains per gallon. That is moderately hard water. The number comes from Iowa City Water Department, dated August 2025.

Iowa City on the hardness scale, with nearby cities
060120180240300360+IA typical 183North Liberty: 49 mg/LNorth Liberty 49Oskaloosa: 110 mg/LOskaloosa 110Bettendorf: 121 mg/LBettendorf 121Hiawatha: 125 mg/LHiawatha 125Cedar Rapids: 128 mg/LCedar Rapids 128Marion: 128 mg/LMarion 128Dubuque: 195 mg/LDubuque 195Davenport: 196 mg/LDavenport 196Muscatine: 240 mg/LMuscatine 240Waterloo: 264 mg/LWaterloo 264Iowa City 76mg/L as calcium carbonate060120180240300360+IA 183North Liberty: 49 mg/LNorth Libe. 49Hiawatha: 125 mg/LHiawatha 125Cedar Rapids: 128 mg/LCedar Rapi. 128Marion: 128 mg/LMarion 128Davenport: 196 mg/LDavenport 196Muscatine: 240 mg/LMuscatine 24076 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Iowa City sits 107 mg/L below the typical Iowa figure of 183. Of the 10 nearest cities we track, 1 has softer water and 9 have harder. The range nearby runs from 49 mg/L in North Liberty to 264 in Waterloo.

What 76 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 Iowa City

3 people × 75 gallons a day × 4.4 gpg = 994 grains a day. A 24,000-grain unit regenerates about every 24 days.

Size it for your household

EPA record for Iowa City's water system

Iowa City Water Department · PWSID IA5225079

No health-based violations since 2016

Serves about 68,753 people from surface water.

Health-based
0
Monitoring or reporting
0
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 Iowa City water hard?

Somewhat. It measures about 76 mg/L (4.4 grains per gallon), which the USGS classes as moderately hard.

What is the water hardness in Iowa City in grains per gallon?

About 4.4 gpg. One grain per gallon equals 17.1 mg/L, so 76 mg/L divided by 17.1 gives 4.4.

What size water softener do I need in Iowa City?

For 3 people using 75 gallons each per day, 4.4 gpg works out to about 994 grains a day. A 24,000-grain softener covers that with a regeneration about every 24 days.

Has the Iowa City water system had EPA violations?

EPA records show no health-based violations for Iowa City Water Department since 2016.

Nearby cities

All 25 cities in Iowa

Hardness data: TapWaterData US Water Hardness (utility report, August 25, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.