Hard water in Marion, OH
County estimate from 834 water samples in Marion County · July 2026
- OH typical
- 113 mg/L
- Softener for 3 people
- 32k grain
- Data
- County estimate
Water samples from around Marion put hardness at about 311 mg/L (18.2 gpg), which would be very hard on the USGS scale. Treat this as a rough guide: it is the median of 834 samples taken across Marion County, mostly wells and streams, not a test of Marion's treated tap water.
Marion sits 198 mg/L above the typical Ohio figure of 113. Of the 10 nearest cities we track, 9 have softer water and 1 has harder. The range nearby runs from 94 mg/L in Delaware to 316 in Marysville.
What 311 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 311 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 × 18.2 gpg = 4,093 grains a day. A 32,000-grain unit regenerates about every 7 days.
EPA record for Marion's water system
We could not match Marion to a community water system in EPA's records. Your water bill or the yearly Consumer Confidence Report names the system and its ID.
Questions
Is Marion water hard?
Yes. It measures about 311 mg/L (18.2 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Marion in grains per gallon?
About 18.2 gpg. One grain per gallon equals 17.1 mg/L, so 311 mg/L divided by 17.1 gives 18.2.
What size water softener do I need in Marion?
For 3 people using 75 gallons each per day, 18.2 gpg works out to about 4,093 grains a day. A 32,000-grain softener covers that with a regeneration about every 7 days.
Nearby cities
- Delaware94 mg/LModerately hard
- Marysville316 mg/LVery hard
- Powell94 mg/LModerately hard
- Mansfield274 mg/LVery hard
- Dublin97 mg/LModerately hard
- Westerville124 mg/LHard
- Worthington97 mg/LModerately hard
- Hilliard97 mg/LModerately hard
- Upper Arlington97 mg/LModerately hard
- New Albany97 mg/LModerately hard
Hardness data: TapWaterData US Water Hardness (county estimate, July 4, 2026), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.