Hard water in Dubuque, IA
County estimate from 109 water samples in Dubuque County · July 2026
- IA typical
- 183 mg/L
- EPA health violations since 2016
- 0
- Softener for 3 people
- 24k grain
- Data
- County estimate
Water samples from around Dubuque put hardness at about 195 mg/L (11.4 gpg), which would be very hard on the USGS scale. Treat this as a rough guide: it is the median of 109 samples taken across Dubuque County, mostly wells and streams, not a test of Dubuque's treated tap water.
Dubuque sits 12 mg/L above the typical Iowa figure of 183. Of the 10 nearest cities we track, 6 have softer water and 4 have harder. The range nearby runs from 49 mg/L in North Liberty to 264 in Waterloo.
What 195 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 195 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 × 11.4 gpg = 2,565 grains a day. A 24,000-grain unit regenerates about every 9 days.
EPA record for Dubuque's water system
No health-based violations since 2016
Serves about 59,667 people from groundwater.
- Health-based
- 0
- Monitoring or reporting
- 0
- Open now
- 0
EPA lists this system as serving Dubuque.
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 Dubuque water hard?
Yes. It measures about 195 mg/L (11.4 grains per gallon), which the USGS classes as very hard.
What is the water hardness in Dubuque in grains per gallon?
About 11.4 gpg. One grain per gallon equals 17.1 mg/L, so 195 mg/L divided by 17.1 gives 11.4.
What size water softener do I need in Dubuque?
For 3 people using 75 gallons each per day, 11.4 gpg works out to about 2,565 grains a day. A 24,000-grain softener covers that with a regeneration about every 9 days.
Has the Dubuque water system had EPA violations?
EPA records show no health-based violations for Dubuque Water Works since 2016.
Nearby cities
- Marion128 mg/LHard
- Hiawatha125 mg/LHard
- Cedar Rapids128 mg/LHard
- Davenport196 mg/LVery hard
- Bettendorf121 mg/LHard
- North Liberty49 mg/LSoft
- Iowa City76 mg/LModerately hard
- Muscatine240 mg/LVery hard
- Waterloo264 mg/LVery hard
- Cedar Falls264 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.