Water hardness in Norman
5.1 gpg moderately hard
Tap water in Norman is moderately hard: 5.1 gpg (88 mg/L · 4.9 °dH · 8.8 °fH).
Source: City of Norman Utilities - Water Quality Information (2024) (2024) · data checked 2026-10-19
Range across supply zones: 71–105 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| Water treatment plant | 4.1 | 71 | moderately hard |
| Well water | 6.1 | 105 | moderately hard |
The City of Norman's water quality information for 2024 gives a hardness of 88 mg/L (5.1 gpg), with a range of 71 to 105 mg/L across two supply zones. The water is moderately hard, and the zones differ only a little. Scale builds slowly. A newer report may change these figures.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 5.1 gpg |
|---|---|
| Utility | City of Norman Utilities (Water Treatment) |
How Norman compares
- Tap water in Norman is 43 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1072 of 1372 in the United States (1 = hardest); 22 % of these cities have softer water.
- In Oklahoma it is number 3 of 3 cities; the regional median is 6.7 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 Norman
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 5 °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 Norman water hard or soft?
It is moderately hard: 88 mg/L as CaCO₃ (5.1 gpg, 4.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Norman 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 Norman water?
5.1 gpg, equal to 4.9 °dH, 8.8 °fH or 88 mg/L calcium carbonate.
What dishwasher salt setting should I use in Norman?
For 88 mg/L (4.9 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Norman?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: City of Norman Utilities - Water Quality Information (2024) (2024). Method: figure published by the water supplier. City of Norman Utilities - Water Quality Information (2024) · Outdated figure? Tell us