Water hardness in Royal Oak
5.8 gpg moderately hard
Tap water in Royal Oak is moderately hard: 5.8 gpg (99 mg/L · 5.5 °dH · 9.9 °fH).
Source: GLWA 2024 Consumer Water Quality Report (hosted by City of Royal Oak) (2024) · data checked 2026-10-20
Range across supply zones: 88–110 mg/L.
3 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| GLWA Lake Huron plant supply | 5.8 | 99 | moderately hard |
| GLWA Northeast plant supply | 5.8 | 99 | moderately hard |
| GLWA Springwells plant supply | 5.9 | 101 | moderately hard |
Royal Oak buys treated water from the Great Lakes Water Authority (GLWA) and its 2024 report lists three plant supplies, Springwells, Northeast and Lake Huron. Their averages are close, 99 to 101 mg/L (about 5.8-5.9 gpg), with samples from 88 to 110 mg/L. The report does not say which plant feeds the city, but the difference is small. Water this hard leaves visible scale on kettles and fixtures over time.
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 Royal Oak (GLWA water via SOCWA) |
How Royal Oak compares
- Tap water in Royal Oak 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, 54 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 Royal Oak
| 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 Royal Oak 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 Royal Oak 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 Royal Oak 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 Royal Oak?
For 99 mg/L (5.5 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Royal Oak?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: GLWA 2024 Consumer Water Quality Report (hosted by City of Royal Oak) (2024). Method: figure published by the water supplier. GLWA 2024 Consumer Water Quality Report (hosted by City of Royal Oak) · Outdated figure? Tell us