Water hardness in Knoxville
5.5 gpg moderately hard
Tap water in Knoxville is moderately hard: 5.5 gpg (94 mg/L · 5.3 °dH · 9.4 °fH).
Source: Knoxville Utilities Board 2025 Water Quality Report (2025) · data checked 2026-10-19
Knoxville Utilities Board's 2025 report lists hardness of 94 mg/L (5.5 gpg) in its additional monitoring table. It is a single value with no range. The water is moderately hard, so expect some scale on kettles and heaters over time.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 5.5 gpg |
|---|---|
| Utility | Knoxville Utilities Board (KUB) |
How Knoxville compares
- Tap water in Knoxville is 39 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 1050 of 1372 in the United States (1 = hardest); 23 % of these cities have softer water.
- In Tennessee it is number 3 of 9 cities; the regional median is 3.8 gpg.
- Nearest city with clearly softer water: Asheville, 130 km away (0.3 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 Knoxville
| 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 Knoxville water hard or soft?
It is moderately hard: 94 mg/L as CaCO₃ (5.5 gpg, 5.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Knoxville 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 Knoxville water?
5.5 gpg, equal to 5.3 °dH, 9.4 °fH or 94 mg/L calcium carbonate.
What dishwasher salt setting should I use in Knoxville?
For 94 mg/L (5.3 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Knoxville?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Knoxville Utilities Board 2025 Water Quality Report (2025). Method: figure published by the water supplier. Knoxville Utilities Board 2025 Water Quality Report · Outdated figure? Tell us