Water hardness in Louisville
7.5 gpg hard
Tap water in Louisville is hard: 7.5 gpg (128 mg/L · 7.2 °dH · 12.8 °fH).
Source: Louisville Water Company 2025 Consumer Confidence Report (2025) · data checked 2026-10-19
Louisville Water's 2025 consumer confidence report gives a hardness of 128 mg/L (7.5 gpg) for the whole system, with no range and no zone split. The supply is Ohio River water. That is hard water, so expect visible scale on kettles and water heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 7.5 gpg |
|---|---|
| Utility | Louisville Water Company |
How Louisville compares
- Tap water in Louisville is 17 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 849 of 1372 in the United States (1 = hardest); 38 % of these cities have softer water.
- In Kentucky it is number 7 of 9 cities; the regional median is 7.8 gpg.
- Nearest city with clearly harder water: Jeffersonville, 10 km away (11.2 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 Louisville
| 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 Louisville water hard or soft?
It is hard: 128 mg/L as CaCO₃ (7.5 gpg, 7.2 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Louisville 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 Louisville water?
7.5 gpg, equal to 7.2 °dH, 12.8 °fH or 128 mg/L calcium carbonate.
What dishwasher salt setting should I use in Louisville?
For 128 mg/L (7.2 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Louisville?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Louisville Water Company 2025 Consumer Confidence Report (2025). Method: figure published by the water supplier. Louisville Water Company 2025 Consumer Confidence Report · Outdated figure? Tell us