Hard water in Sioux City, IA
Reported by Sioux City Water Supply · May 2025
- IA typical
- 183 mg/L
- EPA health violations since 2016
- 5
- Softener for 3 people
- 24k grain
- Data
- Utility report
Tap water in Sioux City has about 183 mg/L of hardness, which is 10.7 grains per gallon. On the USGS scale that counts as very hard. The number comes from Sioux City Water Supply, dated May 2025.
At 183 mg/L, Sioux City is close to the typical Iowa figure of 183 mg/L. Of the 10 nearest cities we track, 8 have softer water and 2 have harder. The range nearby runs from 68 mg/L in Clive to 440 in Fort Dodge.
What 183 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 183 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 × 10.7 gpg = 2,407 grains a day. A 24,000-grain unit regenerates about every 9 days.
EPA record for Sioux City's water system
5 health-based violations since 2016
Serves about 85,791 people from surface water.
- Health-based
- 5
- Monitoring or reporting
- 2
- Open now
- 0
| Contaminant or rule | Violations | Period | Status |
|---|---|---|---|
| Total trihalomethanes (TTHM)a disinfection byproduct | 2 | 2019 | Resolved |
| Epichlorohydrin | 3 | 2016–2017 | 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 Sioux City water hard?
Yes. It measures about 183 mg/L (10.7 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Sioux City in grains per gallon?
About 10.7 gpg. One grain per gallon equals 17.1 mg/L, so 183 mg/L divided by 17.1 gives 10.7.
What size water softener do I need in Sioux City?
For 3 people using 75 gallons each per day, 10.7 gpg works out to about 2,407 grains a day. A 24,000-grain softener covers that with a regeneration about every 9 days.
Has the Sioux City water system had EPA violations?
EPA records show 5 health-based violations for Sioux City Water Supply since 2016, involving Total trihalomethanes (TTHM), Epichlorohydrin. There were also 2 monitoring or reporting violations, which are about late or missing tests and notices.
Nearby cities
- Fort Dodge440 mg/LVery hard
- Waukee302 mg/LVery hard
- Ames150 mg/LHard
- Polk City151 mg/LHard
- Clive68 mg/LModerately hard
- Urbandale99 mg/LModerately hard
- Johnston126 mg/LHard
- West Des Moines135 mg/LHard
- Ankeny120 mg/LModerately hard
- Norwalk132 mg/LHard
Hardness data: TapWaterData US Water Hardness (utility report, May 14, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.