How hard is the water in Cincinnati, OH?

Tap water hardness
113mg/L
6.6gpg
Moderately hard

Reported by Cincinnati Public Water System · March 2025

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

Tap water in Cincinnati has about 113 mg/L of hardness, which is 6.6 grains per gallon. On the USGS scale that counts as moderately hard. The number comes from Cincinnati Public Water System, dated March 2025.

Cincinnati on the hardness scale, with nearby cities
060120180240300360+OH typical 113Monroe: 45 mg/LMonroe 45Hamilton: 105 mg/LHamilton 105Fairfield: 111 mg/LFairfield 111Beckett Ridge: 111 mg/LBeckett Ridge 111Norwood: 113 mg/LNorwood 113Amelia: 130 mg/LAmelia 130The Village of Indian Hill: 150 mg/LThe Village of Indian Hill 150Montgomery: 150 mg/LMontgomery 150Mason: 280 mg/LMason 280Middletown: 303 mg/LMiddletown 303Cincinnati 113mg/L as calcium carbonate060120180240300360+OH 113Fairfield: 111 mg/LFairfield 111Beckett Ridge: 111 mg/LBeckett Ri. 111Norwood: 113 mg/LNorwood 113Amelia: 130 mg/LAmelia 130The Village of Indian Hill: 150 mg/LThe Villag. 150Montgomery: 150 mg/LMontgomery 150113 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 113 mg/L, Cincinnati is close to the typical Ohio figure of 113 mg/L. Of the 10 nearest cities we track, 4 have softer water and 5 have harder. The range nearby runs from 45 mg/L in Monroe to 303 in Middletown.

What 113 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 Cincinnati

3 people × 75 gallons a day × 6.6 gpg = 1,487 grains a day. A 24,000-grain unit regenerates about every 16 days.

Size it for your household

EPA record for Cincinnati's water system

Cincinnati Public Water System · PWSID OH3102612

No health-based violations since 2016

Serves about 800,000 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 Cincinnati water hard?

Somewhat. It measures about 113 mg/L (6.6 grains per gallon), which the USGS classes as moderately hard.

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

About 6.6 gpg. One grain per gallon equals 17.1 mg/L, so 113 mg/L divided by 17.1 gives 6.6.

What size water softener do I need in Cincinnati?

For 3 people using 75 gallons each per day, 6.6 gpg works out to about 1,487 grains a day. A 24,000-grain softener covers that with a regeneration about every 16 days.

Has the Cincinnati water system had EPA violations?

EPA records show no health-based violations for Cincinnati Public Water System since 2016.

Nearby cities

All 108 cities in Ohio

Hardness data: TapWaterData US Water Hardness (utility report, March 31, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.