WaterProfile Local

Utilities / Michigan

Detroit, MI water hardness

Detroit Water and Sewerage Department publishes an average hardness of 107 mg/L for its system, in its Detroit Water and Sewerage Department 2025 Water Quality Report. On the USGS scale that is moderately hard water, though the utility's own range crosses more than one class — it spans moderately hard and hard water from end to end.

Soft Moderate Hard Very hard 0 60 120 180 500+ 107 mg/L Detroit, MI sits in the moderately hard band mg/L as CaCO₃. Bands drawn equal width, so the axis is not linear.
Detroit Water and Sewerage Department published an average of 107 mg/L, with a published range of 96 to 142 mg/L shown as the bar. The plotted point is the published average. Classification bands from the USGS Water Science School.

The published figure, exactly as it appears

This is the hardness line transcribed from the source, with nothing added:

2025 City of Detroit Tap Water Mineral Analysis — Parameter Units Max. Min. Avg. […] Total Hardness ppm 142 96 107

Detroit Water and Sewerage Department, Detroit Water and Sewerage Department 2025 Water Quality Report

Units as published: ppm. What kind of figure it is: an average with a range. Retrieved 2026-10-26.

Detroit 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.

Figuremg/L (ppm)Grains per gallonWhose number
Published average1076.3mg/L published, gpg is our conversion
Low end of published range965.6mg/L published, gpg is our conversion
High end of published range1428.3mg/L published, gpg is our conversion
Plotted on the scale above1076.3published 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: 107 ÷ 17.1 = 6.3 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

UtilityDetroit Water and Sewerage Department
Service area as publishedThe City of Detroit, served by the Detroit Water and Sewerage Department. DWSD distributes water treated by the Great Lakes Water Authority; suburban GLWA customers are served by their own community systems and are not described by this page.
Source waterTreated water purchased from the Great Lakes Water Authority (Detroit River and Lake Huron sources).

Provenance of every number on this page

Source documentDetroit Water and Sewerage Department 2025 Water Quality Report
Source URLhttps://detroitmi.gov/sites/detroitmi.localhost/files/2026-06/DWSD%20-%20WQR%20-%202025%20-%20Final%20-1.pdf
Published byDetroit Water and Sewerage Department (City of Detroit)
Report year2025
Year noteThe hardness row is in the table “2025 City of Detroit Tap Water Mineral Analysis”.
Retrieved2026-10-26
Classification bandsUSGS Water Science School, retrieved 2026-10-16

Notes the report forces on this page

If you are sizing a softener for Detroit water

At 6.3 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 Detroit sits against other verified systems

Soft Soft 0–60
Moderately hard Moderate 61–120
Hard Hard 121–180
Very hard Very hard 181+
  1. Portland, OR 9 mg/L 0.5 gpg Soft
  2. Boston, MA 16 mg/L 1 gpg Soft
  3. Manchester, NH 17.9 mg/L 1 gpg Soft
  4. Seattle, WA 19.1 mg/L 1.1 gpg Soft
  5. Raleigh, NC 25 mg/L 1.47 gpg Soft
  6. New York, NY 32 mg/L 2 gpg Soft
  7. Charlotte, NC 32 mg/L 1.9 gpg Soft
  8. Memphis, TN 46 mg/L 2.7 gpg Soft
  9. Norfolk, VA 48 mg/L 2.8 gpg Soft
  10. Anchorage, AK 56 mg/L 3.3 gpg Soft
  11. Virginia Beach, VA 56 mg/L 3.3 gpg Soft
  12. Oakland, CA 68.4 mg/L 4 gpg Moderately hard
  13. Nashville, TN 77.3 mg/L 4.5 gpg Moderately hard
  14. Sacramento, CA 83 mg/L 4.9 gpg Moderately hard
  15. Fresno, CA 89.3 mg/L 5.2 gpg Moderately hard
  16. Saint Paul, MN 90 mg/L 5 gpg Moderately hard
  17. Austin, TX 93 mg/L 5.4 gpg Moderately hard
  18. Minneapolis, MN 94 mg/L 5.5 gpg Moderately hard
  19. Washington, DC 95 mg/L 5.6 gpg Moderately hard
  20. Baltimore, MD 97.5 mg/L 5.7 gpg Moderately hard
  21. Birmingham, AL 98 mg/L 5.7 gpg Moderately hard
  22. Kansas City, MO 100 mg/L 5.8 gpg Moderately hard
  23. Denver, CO 105 mg/L 6.1 gpg Moderately hard
  24. Detroit, MI 107 mg/L 6.3 gpg Moderately hard
  25. Aurora, CO 113 mg/L 6.6 gpg Moderately hard
  26. Tulsa, OK 114.5 mg/L 6.7 gpg Moderately hard
  27. Louisville, KY 115 mg/L 6.7 gpg Moderately hard
  28. Columbus, OH 120 mg/L 7 gpg Moderately hard
  29. Cleveland, OH 120 mg/L 7 gpg Moderately hard
  30. Philadelphia, PA 125 mg/L 7.3 gpg Hard
  31. Ann Arbor, MI 126 mg/L 7.4 gpg Hard
  32. Cincinnati, OH 133 mg/L 7.8 gpg Hard
  33. Chicago, IL 134.5 mg/L 7.9 gpg Hard
  34. Houston, TX 135.5 mg/L 7.9 gpg Hard
  35. Milwaukee, WI 137 mg/L 8.01 gpg Hard
  36. St. Louis, MO 138 mg/L 8.1 gpg Hard
  37. Grand Rapids, MI 142 mg/L 8.3 gpg Hard
  38. Fort Worth, TX 145 mg/L 8.5 gpg Hard
  39. Spokane, WA 159 mg/L 9.3 gpg Hard
  40. Honolulu, HI 162.5 mg/L 9.5 gpg Hard
  41. Wichita, KS 170 mg/L 9.9 gpg Hard
  42. Omaha, NE 170 mg/L 10 gpg Hard
  43. Los Angeles, CA 192 mg/L 11.2 gpg Very hard
  44. Lincoln, NE 192 mg/L 11.2 gpg Very hard
  45. Riverside, CA 197 mg/L 12 gpg Very hard
  46. Tampa, FL 220 mg/L 12.9 gpg Very hard
  47. Phoenix, AZ 237 mg/L 13.9 gpg Very hard
  48. Mesa, AZ 239.4 mg/L 14 gpg Very hard
  49. Round Rock, TX 258 mg/L 15.1 gpg Very hard
  50. Pflugerville, TX 267 mg/L 15.6 gpg Very hard
  51. San Diego, CA 276 mg/L 16 gpg Very hard
  52. Las Vegas, NV 280 mg/L 16 gpg Very hard
  53. Chandler, AZ 282.2 mg/L 16.5 gpg Very hard
  54. San Antonio, TX 299.3 mg/L 17.5 gpg Very hard
  55. Anaheim, CA 300 mg/L 18 gpg Very hard
  56. Henderson, NV 304 mg/L 18 gpg Very hard
  57. Indianapolis, IN 317 mg/L 19 gpg Very hard
  58. Madison, WI 324.9 mg/L 19 gpg Very hard
  59. Scottsdale, AZ 352.5 mg/L 20.6 gpg Very hard
  60. Salt Lake City, UT 353.5 mg/L 20.7 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.

Detroit, MI is the highlighted row. Every other system on this chart has its own page with its own published figure and report date. Grains per gallon are the utility's own figure where it published one, and our conversion at 17.1 mg/L per grain where it did not.

Systems with similar published hardness

All 60 verified systems   How to find hardness in your own utility's report   If you are on a well instead