Water hardness in Dearborn
5.9 gpg moderately hard
Tap water in Dearborn is moderately hard: 5.9 gpg (102 mg/L · 5.7 °dH · 10.2 °fH).
Source: City of Dearborn 2024 Annual Water Quality Report (CCR), Southwest tap water mineral analysis (2025) · data checked 2026-10-19
Range across supply zones: 88–114 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Southwest Water Treatment Plant (Allen Park) tap water | 6 | 102 | moderately hard |
| Springwells Water Treatment Plant (Warren Ave) tap water | 5.9 | 101 | moderately hard |
Dearborn buys Great Lakes water treated by the Great Lakes Water Authority, and its 2024 report lists two plants. The Southwest plant averages 102 mg/L (5.9 gpg), range 90 to 114, and Springwells averages 101 mg/L (5.9 gpg), range 88 to 110. The page shows the median of the two. The report does not name CaCO3. That is moderately hard water, and scale builds slowly.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 5.9 gpg |
|---|---|
| Utility | City of Dearborn Water and Sewerage Division (GLWA supply) |
How Dearborn compares
- Tap water in Dearborn is 35 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1009 of 1372 in the United States (1 = hardest); 26 % of these cities have softer water.
- In Michigan it is number 21 of 28 cities; the regional median is 6.2 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 Dearborn
| 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 Dearborn water hard or soft?
It is moderately hard: 102 mg/L as CaCO₃ (5.9 gpg, 5.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Dearborn 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 Dearborn water?
5.9 gpg, equal to 5.7 °dH, 10.2 °fH or 102 mg/L calcium carbonate.
What dishwasher salt setting should I use in Dearborn?
For 102 mg/L (5.7 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Dearborn?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: City of Dearborn 2024 Annual Water Quality Report (CCR), Southwest tap water mineral analysis (2025). Method: figure published by the water supplier. City of Dearborn 2024 Annual Water Quality Report (CCR), Southwest tap water mineral analysis · Outdated figure? Tell us