Hard water in Marion, IA
Reported by Cedar Rapids Water Department · July 2025
- IA typical
- 183 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- Utility report
The water in Marion carries roughly 128 mg/L of dissolved calcium and magnesium, or 7.5 grains per gallon. That is hard water. The number comes from Cedar Rapids Water Department, dated July 2025.
Marion sits 55 mg/L below the typical Iowa figure of 183. Of the 10 nearest cities we track, 4 have softer water and 5 have harder. The range nearby runs from 49 mg/L in North Liberty to 264 in Waterloo.
What 128 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 128 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 × 7.5 gpg = 1,685 grains a day. A 24,000-grain unit regenerates about every 14 days.
EPA record for Marion's water system
No health-based violations since 2016
Serves about 41,623 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
EPA lists Marion Municipal Water Dept as the system serving Marion. The hardness figure above comes from a different system's report, which TapWaterData uses for Marion.
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 Marion water hard?
Yes. It measures about 128 mg/L (7.5 grains per gallon), which the USGS classes as hard.
What is the water hardness in Marion in grains per gallon?
About 7.5 gpg. One grain per gallon equals 17.1 mg/L, so 128 mg/L divided by 17.1 gives 7.5.
What size water softener do I need in Marion?
For 3 people using 75 gallons each per day, 7.5 gpg works out to about 1,685 grains a day. A 24,000-grain softener covers that with a regeneration about every 14 days.
Has the Marion water system had EPA violations?
EPA records show no health-based violations for Marion Municipal Water Dept since 2016.
Nearby cities
- Hiawatha125 mg/LHard
- Cedar Rapids128 mg/LHard
- North Liberty49 mg/LSoft
- Iowa City76 mg/LModerately hard
- Waterloo264 mg/LVery hard
- Muscatine240 mg/LVery hard
- Dubuque195 mg/LVery hard
- Cedar Falls264 mg/LVery hard
- Davenport196 mg/LVery hard
- Bettendorf121 mg/LHard
Hardness data: TapWaterData US Water Hardness (utility report, July 30, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.