Tampa, FL water hardness

Name: Tampa, FL water hardness as published by City of Tampa Water Department
Creator: City of Tampa Water Department
License: https://www.usa.gov/government-works

City of Tampa Water Department publishes a hardness range of 140 to 300 mg/L for its system, on the page cited below. On the USGS scale that is very hard water, though the utility's own range crosses more than one class — it spans hard and very hard water from end to end.

City of Tampa Water Department published a range of 140 to 300 mg/L, shown as the bar. The plotted point is the midpoint of the published range (no average is published). 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:

The hardness of Tampa's drinking water, primarily taken from the Hillsborough River, fluctuates throughout the year -- lower during the wet season and higher in the dry season -- between about 140 to 300 parts per million or 8 to 17 grains per gallon (one grain per gallon equals 17.2 parts per million).
City of Tampa Water Department

Units as published: parts per million, with grains per gallon given alongside. What kind of figure it is: a range with no average. Retrieved 2026-10-17.

Tampa 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 range	140	8	both published by the utility
High end of published range	300	17	both published by the utility
Plotted on the scale above	220	12.9	midpoint of the published range (no average is published); 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: 220 ÷ 17.1 = 12.9 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 Tampa Water Department
Service area as published	The City of Tampa Water Department's system. The fact sheet names no sub-area and no treatment plant.
Source water	Primarily the Hillsborough River, per the department's own fact sheet.

Provenance of every number on this page

Source document	City of Tampa Water Department, “Understanding Water Hardness”
Source URL	https://www.tampa.gov/sites/default/files/document/2026/understanding-water-hardness.pdf
Published by	City of Tampa Water Department
Report year	Not stated on the source page
Year note	The fact sheet states no year. The same passage appears on the department's Frequently Asked Questions page.
Retrieved	2026-10-17
Classification bands	USGS Water Science School, retrieved 2026-10-16

Notes the report forces on this page

The department states the figure fluctuates seasonally — lower in the wet season, higher in the dry season — so this is a seasonal span rather than a sampling range at one point in time.
Tampa prints its own conversion factor as “one grain per gallon equals 17.2 parts per million”. This site converts at 17.1 everywhere, so a grains figure worked here can differ slightly from one worked with Tampa's factor. Both of Tampa's own figures are shown as published.
The published span crosses two USGS classes: 140 ppm is hard and 300 ppm is very hard.

If you are sizing a softener for Tampa water

At 12.9 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 Tampa 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.

Tampa, FL 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

Phoenix, AZ City of Phoenix Water Services Department, 237 mg/L (13.9 gpg)
Mesa, AZ City of Mesa Water Resources, 239.4 mg/L (14 gpg)
Los Angeles, CA Los Angeles Department of Water and Power, 192 mg/L (11.2 gpg)
Lincoln, NE Lincoln Water System, 192 mg/L (11.2 gpg)

All 44 verified systems How to find hardness in your own utility's report If you are on a well instead