Water hardness in Dubuque
5.8 gpg moderately hard
Tap water in Dubuque is moderately hard: 5.8 gpg (100 mg/L · 5.6 °dH · 10 °fH).
Source: City of Dubuque Water Department, Treatment Process web page (2026) · data checked 2026-10-23
Dubuque draws its water from shallow wells near the Mississippi and from the deeper Jordan aquifer, and softens it with lime at the Eagle Point plant. Raw well water here is around the very hard level, so the softened supply of 100 mg/L CaCO₃ is a reduced figure. Expect some scale in kettles and heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 5.8 gpg |
|---|---|
| Utility | City of Dubuque Water Department (Eagle Point Water Treatment Plant) |
How Dubuque compares
- Tap water in Dubuque is 36 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1015 of 1372 in the United States (1 = hardest); 26 % of these cities have softer water.
- In Iowa it is number 5 of 5 cities; the regional median is 8 gpg.
- Nearest city with clearly softer water: Lyndon Station, 148 km away (1.9 gpg).
- Nearest city with clearly harder water: Dickeyville, 15 km away (20.9 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Dubuque
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 6 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Dubuque water hard or soft?
It is moderately hard: 100 mg/L as CaCO₃ (5.8 gpg, 5.6 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Dubuque safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Dubuque water?
5.8 gpg, equal to 5.6 °dH, 10 °fH or 100 mg/L calcium carbonate.
What dishwasher salt setting should I use in Dubuque?
For 100 mg/L (5.6 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Dubuque?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: City of Dubuque Water Department, Treatment Process web page (2026). Method: figure published by the water supplier. City of Dubuque Water Department, Treatment Process web page · Outdated figure? Tell us