Tulsa, OK water hardness

Name: Tulsa, OK water hardness as published by City of Tulsa Water and Sewer
Creator: City of Tulsa Water and Sewer
License: https://www.usa.gov/government-works

City of Tulsa Water and Sewer does not publish one hardness figure for Tulsa. It publishes 2 separate figures, one per plant, on the page cited below. Across them the published numbers run from 89 to 140 mg/L. On the USGS scale those figures are not all in one class: they span moderately hard and hard water, so which class describes an address depends on which plant serves it. Every published figure is in the table below.

City of Tulsa Water and Sewer published a figure for each of 2 plants rather than one for the system; the bar spans the lowest and highest of those published figures, 89 to 140 mg/L. The plotted point is the midpoint of the lowest and highest figures published across this system's 2 areas; the utility publishes no system-wide figure, so this midpoint is not one of its numbers. Classification bands from the USGS Water Science School.

Every figure City of Tulsa Water and Sewer publishes, by plant

These are the only hardness numbers this utility publishes. There is no system-wide figure to quote, so the figure plotted above is a midpoint we calculated from the lowest and highest of them, and it is labelled as such everywhere it appears.

Plant as published	mg/L (ppm)	Grains per gallon	USGS class
Mohawk Water Treatment Plant	89	5.2	Moderately hard
A.B. Jewell Water Treatment Plant	140	8.2	Hard

Figures in the grains column are the utility's own where it published them. Where it published only one unit, the other column is our conversion at 17.1 mg/L per grain, and the row above says which. Nothing in this table is averaged across plants.

The published figures, exactly as they appear

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

The average hardness for A.B. Jewell runs 8.2 grains per gallon or 140 parts per million. […] The average hardness for Mohawk runs 5.2 grains per gallon or 89 parts per million.
City of Tulsa Water and Sewer

Units as published: grains per gallon, with parts per million given alongside. What kind of figure it is: a single value. Retrieved 2026-10-17.

Tulsa 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
Low end of published span across areas	89	5.2	both published by the utility
High end of published span across areas	140	8.2	both published by the utility
Plotted on the scale above	114.5	6.7	midpoint of the lowest and highest figures published across this system's 2 areas; the utility publishes no system-wide figure, so this midpoint is not one of its numbers; 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: 114.5 ÷ 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	City of Tulsa Water and Sewer
Service area as published	The City of Tulsa's water system, supplied by two treatment plants. The page tells readers to check the city's water service area map to see whether the A.B. Jewell or the Mohawk plant supplies their water.

Provenance of every number on this page

Source document	City of Tulsa, “Frequently Asked Questions About Water”
Source URL	https://www.cityoftulsa.org/government/departments/water-and-sewer/water-supply/faqs-about-water/
Published by	City of Tulsa Water and Sewer
Report year	Not stated on the source page
Year note	The page states no year for the plant hardness averages and cites no report.
Retrieved	2026-10-17
Classification bands	USGS Water Science School, retrieved 2026-10-16

Notes the report forces on this page

Tulsa publishes a figure per treatment plant and no single system-wide figure. The plotted point is the midpoint of the two published plant averages and is not itself a City of Tulsa number.
The two plants fall in different USGS classes: Mohawk at 89 ppm is moderately hard and A.B. Jewell at 140 ppm is hard. Which classification applies depends on which plant serves an address.
The page states no year and cites no report.

If you are sizing a softener for Tulsa 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 Tulsa sits against other verified systems

Soft Soft 0–60

Moderately hard Moderate 61–120

Hard Hard 121–180

Very hard Very hard 181+

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.

Tulsa, OK 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

Louisville, KY Louisville Water Company, 115 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