Tempe's water and how hard your softener has to work
Tempe Water Utilities serves Tempe and Guadalupe, mostly with Salt and Verde river water. Its 2025 average is very hard, and its highest readings were far harder.
Tempe water hardness by area
Figures published by City of Tempe Water Utilities. The dial setting is the number to enter on your softener.
| City or area | How hard | Range (grains per gallon) | Softener dial setting | Source |
|---|---|---|---|---|
| Tempe | Very hard | 10.4 to 32.6, average 12.3 | 13 | City of Tempe Water Utilities, annual water quality report, 2026 (2025 data) |
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2. How many people live in your home?
What the dial setting means
Every softener has a control valve on top with a setting for your water's hardness, usually labelled "hardness" or "grains". Enter this number there. It tells the softener how hard your water is, so it knows when it is full.
"Recharging" (some manuals say "regenerating") is the softener cleaning itself: it rinses its resin beads with salty water to flush out the minerals they have caught. With this setting it happens on its own, about every 8 days in your home, usually at night.
Set the number too low and hard water slips through before the next recharge. Set it too high and the softener recharges early, wasting salt and water.
Tempe's average is 12.3; the report's highest single reading was far higher, so a home test helps. Source: City of Tempe Water Utilities, annual water quality report, 2026 (2025 data).
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How this figure was measured
Who published it
What the figure is
How we use it
Three sources, mostly river
In 2025, according to the city, about 79 percent of Tempe and Guadalupe’s water was Salt and Verde river water from the Salt River Project, about 14 percent came from eight city wells, and 7 percent was Colorado River water through the Central Arizona Project. The city’s own explanation of hardness notes that the Verde River carries more hardness than the Salt.
The high reading
Most of Tempe’s readings sit close to the 12.3 average; the low was 10.4. The highest, 32.6 grains per gallon, is more than double the average, and the report doesn’t say where or when it was measured. It is a good reason not to rely only on a citywide figure: if your fixtures scale up fast, test your own tap.
Sizing in Tempe
At 12.3 grains per gallon a family of four needs a 32,000-grain softener, recharging about every 8 days on roughly 11 bags of salt a year. A home of three manages with 24,000 grains. If your test reads 20 or more, the same family of four needs about 48,000 grains.
Close to Mesa’s City Zone
Tempe’s average is close to Mesa’s City Zone (about 12), which is fed by the same Salt River Project canals, and lower than Chandler’s citywide average of 16.5.
Common questions
- How hard is Tempe water?
- Tempe Water Utilities' 2025 report gives an average of 12.3 grains per gallon (211 ppm), with a range of 10.4 to 32.6.
- Why does Tempe's range go so high?
- The report doesn't say where the 32.6 reading came from. Tempe blends river water with water from eight wells, and the city notes that Verde River water is higher in hardness than Salt River water.
- Does Tempe recommend a softener setting?
- Not a number, but its questions page explains the conversion: divide the hardness in mg/L by 17.1 to get grains per gallon.