Phoenix hard water, city by city
Every Valley city publishes its own hardness figure. Here they are side by side, with where each city's water comes from and what the numbers mean for your home.
Water hardness in Phoenix and nearby cities
From each city's own published figures. The dial setting is the hardness rounded up: the number to enter on your softener.
| City or area | How hard | Range (grains per gallon) | Softener dial setting | Source |
|---|---|---|---|---|
| Phoenix | Very hard | 10 to 17.6 | 14 | City of Phoenix Water Services Department, annual water quality report, 2025 |
| Scottsdale, south of Indian School Rd | Very hard | 13 to 15 | 14 | Scottsdale Water (City of Scottsdale), annual water quality report, 2026 (2025 data) |
| Scottsdale, Indian School to Chaparral Rd | Very hard | 13 to 17 | 15 | Scottsdale Water (City of Scottsdale), annual water quality report, 2026 (2025 data) |
| Scottsdale, north of Chaparral Rd | Very hard | 13 to 17 | 15 | Scottsdale Water (City of Scottsdale), annual water quality report, 2026 (2025 data) |
| Mesa, City Zone | Very hard | about 12 | 12 | City of Mesa Water Resources Department, annual water quality report, 2025 |
| Mesa, Eastern and Southern Zones | Very hard | about 16 | 16 | City of Mesa Water Resources Department, annual water quality report, 2025 |
| Chandler | Very hard | 5 to 20, average 16.5 | 17 | City of Chandler, water quality questions and answers, undated web page |
| Peoria | Very hard | 5.1 to 19.7 | 13 | City of Peoria Water Services Department, hardness study, 2020 |
| Gilbert | Very hard | 6.6 to 17.5, average 10.8 | 11 | Town of Gilbert Public Works (Water), annual water quality report, 2026 (2025 data) |
| Glendale | Very hard | 5.4 to 18.5, average 13.8 | 14 | City of Glendale Water Services Department, annual water quality report, 2026 (2025 data) |
| Tempe | Very hard | 10.4 to 32.6, average 12.3 | 13 | City of Tempe Water Utilities, annual water quality report, 2026 (2025 data) |
| Surprise, Mountain Vista | Moderately hard | 2.7 to 4.9, average 3.9 | 4 | City of Surprise Water Resource Management, annual water quality report, 2026 (2025 data) |
| Surprise, Desert Oasis | Moderately hard | 2.6 to 11.1, average 6.2 | 7 | City of Surprise Water Resource Management, annual water quality report, 2026 (2025 data) |
| Surprise, Surprise Foothills | Moderately hard | 5.1 to 5.6, average 5.3 | 6 | City of Surprise Water Resource Management, annual water quality report, 2026 (2025 data) |
| Surprise, Circle City | Hard | about 8.2 | 9 | City of Surprise Water Resource Management, annual water quality report, 2026 (2025 data) |
| Queen Creek | Very hard | 6 to 17 | 12 | Town of Queen Creek Water Services, water quality questions and answers, undated web page |
| Fountain Hills | Very hard | about 16 | 16 | EPCOR Water Arizona (Chaparral City water system), annual water quality report, 2025 (hardness sampled in 2024) |
Reading the hardness numbers
Utilities report hardness in parts per million (ppm) or milligrams per litre, which are the same thing, and sometimes in grains per gallon. Softeners use grains per gallon. To convert, divide ppm by 17.1: the top of Phoenix’s range, 302 ppm, is 17.6 grains per gallon.
| Grains per gallon | What we call it |
|---|---|
| Under 3.5 | Soft |
| 3.5 to 7 | Moderately hard |
| 7 to 10.5 | Hard |
| 10.5 to 17 | Very hard |
| Over 17 | Extremely hard |
The bands up to 10.5 and “very hard” follow the U.S. Geological Survey. Splitting off “extremely hard” above 17 is our own choice, to separate the hardest Valley water.
Why Phoenix water changes from one month to the next
Phoenix mixes three rivers and a small amount of well water, and the balance between them can shift. The city publishes a range for its whole system rather than one number. We size softeners with the middle of the range; if your fixtures scale up quickly, test your own water.
What hard water does around the house
Hard water leaves white scale on faucets, showerheads and glass, spots on dishes, and a crust inside water heaters and kettles. Soap and shampoo lather less. These are plumbing and cleaning problems, and they are what a water softener is for.
Common questions
- Is Phoenix tap water hard or soft?
- Hard. At 10 to 17.6 grains per gallon, Phoenix city water is well above the 7 grains per gallon where the U.S. Geological Survey scale starts calling water hard.
- Why is Phoenix water so hard?
- Phoenix drinks river water from the Salt, Verde and Colorado rivers that carries dissolved calcium and magnesium. In 2025 the city got about 97 to 99 percent of its water from these rivers, through the Salt River Project canals and the Central Arizona Project aqueduct, and the rest from about 20 wells.
- Which Phoenix-area city has the hardest water?
- Of the cities we have collected, Chandler has the highest published average at 16.5 grains per gallon. Single neighborhoods can go higher: one of Peoria's 48 test sites averaged 19.7.