Tucson Water classes its water as "hard to very hard." Its parameter guide uses this scale (mg/L as calcium carbonate): 0–60 soft, 60–120 moderate, 120–180 hard, 180+ very hard.1
For the main system, the 2024 Annual Water Quality Report puts hardness at roughly 228 mg/L, about 13.3 grains per gallon.2,3 That's in the "very hard" band. Hardness varies across the system, so your house may read differently.
Converting ppm to grains per gallon
Softeners and dishwashers are set in grains per gallon (gpg). Tucson Water's conversion: divide the mg/L (ppm) figure by 17.1.1 Example: 228 ÷ 17.1 ≈ 13.3 gpg.
Find the number for your address
The City of Tucson has an interactive water-quality map. Enter your street address and it shows results from a nearby sample point, including grains per gallon for setting a softener.4
Is hard water a health problem?
Tucson Water says there are no health concerns linked to calcium carbonate levels. Hard water can still be a household nuisance, with scale and a chalky or mineral aftertaste.1 It also notes that a softener swaps calcium and magnesium for other substances, often sodium.1
What to do next
- Look up your address on the city map, or ask a dealer for a free in-home test.
- Read Water softener vs. reverse osmosis to decide what you need.
- Compare verified Tucson dealers.
Sources
- Tucson Water: water quality parameter explanation table
- Tucson Water 2024 Annual Water Quality Report (Main System)
- Tucson Water Pros: summary of the 2024 report (≈228 ppm / 13.3 gpg)
- City of Tucson: interactive water quality lookup
Last reviewed Oct 13, 2026. This is general information, not professional advice. Confirm figures with your utility and installer.