Louisville, KY water hardness
Louisville Water Company publishes an average hardness of 115 mg/L (6.7 grains per gallon, also its own figure) for its system, in its Louisville Water Company 2024 Water Quality Report. On the USGS scale that is moderately hard water.
The published figure, exactly as it appears
This is the hardness line transcribed from the source, with nothing added:
Hardness (as CaCO3) (ppm) 115 (6.7 grains per gallon)
Louisville Water Company, Louisville Water Company 2024 Water Quality Report
Units as published: ppm, with grains per gallon given alongside. What kind of figure it is: an average with no range. Retrieved 2026-10-17.
Louisville hardness in mg/L and grains per gallon
Water-quality reports use mg/L (identical to ppm). Softener instructions and plumbing specifications use grains per gallon. Both are below. Where a figure is our arithmetic rather than the utility's own number, it says so.
| Figure | mg/L (ppm) | Grains per gallon | Whose number |
|---|---|---|---|
| Published average | 115 | 6.7 | both published by the utility |
| Plotted on the scale above | 115 | 6.7 | published average; the gpg here is our conversion at 17.1, so it can differ slightly from a utility’s own rounded gpg figure |
The conversion, both ways: gpg = mg/L ÷ 17.1 and mg/L = gpg × 17.1. Worked for this system: 115 ÷ 17.1 = 6.7 gpg. The converter does °dH and °f as well, and why the factor is 17.1 explains where the number comes from.
What this figure does not tell you
Service area and source water
| Utility | Louisville Water Company |
|---|---|
| Public water system ID | KY0560258 |
| Service area as published | Louisville Water Company's system, PWSID KY0560258. |
Provenance of every number on this page
| Source document | Louisville Water Company 2024 Water Quality Report |
|---|---|
| Source URL | https://louisvillewater.com/wp-content/uploads/2025/04/LW-CCR-2024-Final-Report.pdf |
| Published by | Louisville Water Company |
| Report year | 2024 |
| Year note | The hardness line sits in the report's “Additional water quality data - 2024” table rather than in its regulated-substances tables. |
| Retrieved | 2026-10-17 |
| Classification bands | USGS Water Science School, retrieved 2026-10-16 |
Notes the report forces on this page
- The report publishes an average and no sampling range, so no range is shown on this page.
- The report gives the 115 ppm figure as an average of the finished water from the Crescent Hill and B.E. Payne treatment plants, not as a figure for either plant on its own.
- 115 divided by 17.1 is 6.7, which matches the utility's own grains-per-gallon figure.
If you are sizing a softener for Louisville water
At 6.7 gpg, the sizing arithmetic starts from your household's water use, not from the hardness alone. The calculator below is pre-filled with this system's figure and every other input is an editable assumption.
Whether a softener is worth installing at this hardness is a judgement, not arithmetic, and it is not one this site makes for you. Nothing here has been tested by the author.
Where Louisville sits against other verified systems
- Portland, OR 9 mg/L 0.5 gpg Soft
- Boston, MA 16 mg/L 1 gpg Soft
- Manchester, NH 17.9 mg/L 1 gpg Soft
- Raleigh, NC 25 mg/L 1.47 gpg Soft
- New York, NY 32 mg/L 2 gpg Soft
- Charlotte, NC 32 mg/L 1.9 gpg Soft
- Memphis, TN 46 mg/L 2.7 gpg Soft
- Anchorage, AK 56 mg/L 3.3 gpg Soft
- Oakland, CA 68.4 mg/L 4 gpg Moderately hard
- Nashville, TN 77.3 mg/L 4.5 gpg Moderately hard
- Sacramento, CA 83 mg/L 4.9 gpg Moderately hard
- Fresno, CA 89.3 mg/L 5.2 gpg Moderately hard
- Saint Paul, MN 90 mg/L 5 gpg Moderately hard
- Austin, TX 93 mg/L 5.4 gpg Moderately hard
- Washington, DC 95 mg/L 5.6 gpg Moderately hard
- Birmingham, AL 98 mg/L 5.7 gpg Moderately hard
- Kansas City, MO 100 mg/L 5.8 gpg Moderately hard
- Denver, CO 105 mg/L 6.1 gpg Moderately hard
- Tulsa, OK 114.5 mg/L 6.7 gpg Moderately hard
- Louisville, KY 115 mg/L 6.7 gpg Moderately hard
- Columbus, OH 120 mg/L 7 gpg Moderately hard
- Cleveland, OH 120 mg/L 7 gpg Moderately hard
- Philadelphia, PA 125 mg/L 7.3 gpg Hard
- Ann Arbor, MI 126 mg/L 7.4 gpg Hard
- Cincinnati, OH 133 mg/L 7.8 gpg Hard
- Milwaukee, WI 137 mg/L 8.01 gpg Hard
- St. Louis, MO 138 mg/L 8.1 gpg Hard
- Fort Worth, TX 145 mg/L 8.5 gpg Hard
- Honolulu, HI 162.5 mg/L 9.5 gpg Hard
- Wichita, KS 170 mg/L 9.9 gpg Hard
- Omaha, NE 170 mg/L 10 gpg Hard
- Los Angeles, CA 192 mg/L 11.2 gpg Very hard
- Lincoln, NE 192 mg/L 11.2 gpg Very hard
- Tampa, FL 220 mg/L 12.9 gpg Very hard
- Phoenix, AZ 237 mg/L 13.9 gpg Very hard
- Mesa, AZ 239.4 mg/L 14 gpg Very hard
- San Diego, CA 276 mg/L 16 gpg Very hard
- Las Vegas, NV 280 mg/L 16 gpg Very hard
- Chandler, AZ 282.2 mg/L 16.5 gpg Very hard
- San Antonio, TX 299.3 mg/L 17.5 gpg Very hard
- Anaheim, CA 300 mg/L 18 gpg Very hard
- Indianapolis, IN 317 mg/L 19 gpg Very hard
- Madison, WI 324.9 mg/L 19 gpg Very hard
- Scottsdale, AZ 352.5 mg/L 20.6 gpg Very hard
mg/L as calcium carbonate. Each classification band is drawn the same width, so the axis is not linear in mg/L.
Systems with similar published hardness
- Tulsa, OK City of Tulsa Water and Sewer, 114.5 mg/L (6.7 gpg)
- Columbus, OH City of Columbus Division of Water, 120 mg/L (7 gpg)
- Cleveland, OH Cleveland Water, 120 mg/L (7 gpg)
- Denver, CO Denver Water, 105 mg/L (6.1 gpg)
All 44 verified systems How to find hardness in your own utility's report If you are on a well instead