Mesa hard water: 12 to 16 grains per gallon
Mesa tap water is very hard: about 12 grains per gallon in the City Zone and 16 in the Eastern and Southern Zones. Those averages come from the City of Mesa's 2025 water quality report (PDF, opens in new tab).
Mesa water hardness
Grains per gallon, from the City of Mesa 2025 water quality report. Sacramento river water shown for comparison.
Where does Mesa water come from?
The city's report splits Mesa into three zones. The City Zone gets Salt and Verde river water through the Salt River Project, treated at the Val Vista plant. That was about 40 percent of Mesa's water in 2025. The Eastern and Southern Zones get Colorado River water through the Central Arizona Project, treated at the Brown Road and Signal Butte plants. That was about 52 percent.
Eighteen deep wells also supply the City Zone. The city says any zone can get well water or a blend at times, and the wells vary in hardness. That is why the report's hardness range is so wide. The report has a zone map on page 5.
What this means at home
- Thick white scale on faucets, shower heads and tile
- Spots on dishes, cars and windows
- Scale inside water heaters and evaporative coolers
- Appliances and fixtures that wear out sooner
Do you need a water softener in Mesa?
For most homes, yes. At 12 to 16 grains per gallon, Mesa water builds scale fast, and the city itself suggests a softener setting of 16. A softener protects your water heater and cuts down on cleaning. Test your tap so the system fits your zone.
Want better drinking water too? Read reverse osmosis vs. a water softener, or see what a softener costs.
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Book my free water testCommon questions
Is Mesa water hard?
Yes, very. The City of Mesa's 2025 report says the City Zone averages about 12 grains per gallon and the Eastern and Southern Zones average about 16. Anything over 10.5 is very hard.
What softener setting should I use in Mesa?
The city recommends setting your softener at 16 grains per gallon, then adjusting it to suit your needs. A test at your tap helps you fine-tune it.
Why does Mesa hardness change during the year?
Mesa uses river water and well water. The city says every zone may get groundwater or a blend at different times of the year, and its wells vary in mineral content.
Keep reading
DataWater hardness by cityHow hard the tap water is in US cities, from each utility report.
City dataPhoenix water hardness: what the city report says10 to 17.6 grains per gallon. Hard to very hard.
GuideHow much does a water softener cost installed?Installed price ranges, running costs, and what drives the price.
GuideReverse osmosis vs. water softener: which one do you need?They do different jobs. Here is how to pick.