Water hardness in Flint
5.8 gpg moderately hard
Tap water in Flint is moderately hard: 5.8 gpg (99 mg/L · 5.5 °dH · 9.9 °fH).
Source: Great Lakes Water Authority 2024 Consumer Water Quality Report, 2024 Lake Huron Tap Water Mineral Analysis (copy hosted by City of Royal Oak) (2024) · data checked 2026-10-23
Range across supply zones: 88–106 mg/L.
Flint buys treated water from the Great Lakes Water Authority, which draws on Lake Huron and the Detroit River. Great Lakes water reflects carbonate rock in its basin, and the reported 99 mg/L CaCO₃ (88–106 mg/L) is moderately hard. 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 Flint Water Department (treated by Great Lakes Water Authority) |
How Flint compares
- Tap water in Flint is 36 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1023 of 1372 in the United States (1 = hardest); 25 % of these cities have softer water.
- In Michigan it is number 24 of 28 cities; the regional median is 6.2 gpg.
- Nearest city with clearly harder water: Ann Arbor, MI, 81 km away (7.4 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 Flint
| 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 Flint water hard or soft?
It is moderately hard: 99 mg/L as CaCO₃ (5.8 gpg, 5.5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Flint 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 Flint water?
5.8 gpg, equal to 5.5 °dH, 9.9 °fH or 99 mg/L calcium carbonate.
What dishwasher salt setting should I use in Flint?
For 99 mg/L (5.5 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Flint?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Great Lakes Water Authority 2024 Consumer Water Quality Report, 2024 Lake Huron Tap Water Mineral Analysis (copy hosted by City of Royal Oak) (2024). Method: figure published by the water supplier. Great Lakes Water Authority 2024 Consumer Water Quality Report, 2024 Lake Huron Tap Water Mineral Analysis (copy hosted by City of Royal Oak) · Outdated figure? Tell us