Hard water in Lima, OH
County estimate from 1,334 water samples in Allen County · July 2026
- OH typical
- 113 mg/L
- EPA health violations since 2016
- 4
- Softener for 3 people
- 32k grain
- Data
- County estimate
Water samples from around Lima put hardness at about 301 mg/L (17.6 gpg), which would be very hard on the USGS scale. Treat this as a rough guide: it is the median of 1,334 samples taken across Allen County, mostly wells and streams, not a test of Lima's treated tap water. One more reason for caution: EPA lists Lima's water system as using surface water, which is often softer than the wells behind the county figure.
At 301 mg/L, Lima is 188 mg/L above the typical Ohio figure of 113. Of the 10 nearest cities we track, 4 have softer water and 6 have harder. The range nearby runs from 49 mg/L in Piqua to 380 in Bryan.
What 301 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 301 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 × 17.6 gpg = 3,960 grains a day. A 32,000-grain unit regenerates about every 8 days.
EPA record for Lima's water system
4 health-based violations since 2016
Serves about 65,619 people from surface water.
- Health-based
- 4
- Monitoring or reporting
- 3
- Open now
- 0
EPA lists this system as serving Lima.
| Contaminant or rule | Violations | Period | Status |
|---|---|---|---|
| Surface Water Treatment Rulefiltration and disinfection | 2 | 2016–2026 | Resolved |
| Total trihalomethanes (TTHM)a disinfection byproduct | 2 | 2022–2024 | Resolved |
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 Lima water hard?
Yes. It measures about 301 mg/L (17.6 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Lima in grains per gallon?
About 17.6 gpg. One grain per gallon equals 17.1 mg/L, so 301 mg/L divided by 17.1 gives 17.6.
What size water softener do I need in Lima?
For 3 people using 75 gallons each per day, 17.6 gpg works out to about 3,960 grains a day. A 32,000-grain softener covers that with a regeneration about every 8 days.
Has the Lima water system had EPA violations?
EPA records show 4 health-based violations for Lima City since 2016, involving Surface Water Treatment Rule, Total trihalomethanes (TTHM). There were also 3 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Sidney342 mg/LVery hard
- Findlay138 mg/LHard
- Piqua49 mg/LSoft
- Troy328 mg/LVery hard
- Bowling Green265 mg/LVery hard
- Marion311 mg/LVery hard
- Marysville316 mg/LVery hard
- Bryan380 mg/LVery hard
- Waterville110 mg/LModerately hard
- Springfield360 mg/LVery 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.