Water hardness in Ann Arbor, MI
7.4 gpg hard
Tap water in Ann Arbor, MI is hard: 7.4 gpg (126 mg/L · 7.1 °dH · 12.6 °fH).
Source: City of Ann Arbor 2025 Consumer Confidence Report (2025) · data checked 2026-10-19
Range across supply zones: 74–180 mg/L.
The City of Ann Arbor's 2025 Consumer Confidence Report lists an average hardness of 126 mg/L as CaCO3 (7.4 gpg), with results from 74 to 180 mg/L. That is moderately hard water, and it shifts over the year. Expect some scale on kettles and fixtures; whether a softener pays off depends on where you sit in that range.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 7.4 gpg |
|---|---|
| Utility | City of Ann Arbor Water Treatment Services |
How Ann Arbor, MI compares
- Tap water in Ann Arbor, MI is 19 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 858 of 1372 in the United States (1 = hardest); 37 % of these cities have softer water.
- In Michigan it is number 7 of 28 cities; the regional median is 6.2 gpg.
- Nearest city with clearly softer water: Royal Oak, 54 km away (5.8 gpg).
Ranking of the hardest and softest water in the United States →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Ann Arbor, MI
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 7 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H2 |
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 Ann Arbor, MI water hard or soft?
It is hard: 126 mg/L as CaCO₃ (7.4 gpg, 7.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Ann Arbor, MI 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 Ann Arbor, MI water?
7.4 gpg, equal to 7.1 °dH, 12.6 °fH or 126 mg/L calcium carbonate.
What dishwasher salt setting should I use in Ann Arbor, MI?
For 126 mg/L (7.1 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Ann Arbor, MI?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: City of Ann Arbor 2025 Consumer Confidence Report (2025). Method: figure published by the water supplier. City of Ann Arbor 2025 Consumer Confidence Report · Outdated figure? Tell us