Is Phoenix water hard? Yes. The City of Phoenix 2025 water quality report gives total hardness of 172 to 302 ppm, which it also states as 10 to 17.6 grains per gallon. On the USGS scale, the low end of that range is hard and everything above 180 mg/L is very hard.
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The figure, and where it comes from
The number is from the City of Phoenix Water Services report for 2025, which lists total hardness as “172 – 302 / 10 – 17.6” in ppm and grains per gallon. It applies to City of Phoenix customers. In 2025 about 97 to 99% of the city’s water came from surface water, the Salt, Verde and Colorado rivers, with about 2% from about 20 city wells. The Colorado River water arrives through the Central Arizona Project and the Salt and Verde water through the Salt River Project canals.
What hard water is
Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals, the USGS explains. Its general guidelines grade water in milligrams per liter as calcium carbonate:
| mg/L as calcium carbonate | About grains per gallon | USGS name |
|---|---|---|
| 0 to 60 | 0 to 3.5 | Soft |
| 61 to 120 | 3.5 to 7 | Moderately hard |
| 121 to 180 | 7 to 10.5 | Hard |
| Over 180 | Over 10.5 | Very hard |
One grain per gallon is about 17 mg/L. EPA’s secondary standards table has no number for hardness, but it lists hardness among the effects of high total dissolved solids, for which its guideline is 500 mg/L. The city’s 2025 report gives dissolved solids of 464 to 716 ppm.
What it does in a home
The city’s report says hard water can cause some types of scaling in pipes and water heaters, and on plumbing fixtures. The USGS adds that soap reacts with the calcium in hard water to form soap scum, so more soap or detergent is needed to get things clean.
- White crust around faucets and showerheads.
- Spots and film on glasses and shower doors.
- Soap scum in tubs and sinks.
- Scale inside water heaters, as the city’s report notes.
Is hard water a health problem?
The City of Phoenix report says: “Taste, odor and hardness are not regulated under drinking water health standards.” Hardness is about scale and soap. For questions about your own health, ask your doctor.
Tired of the scale? Ask a local pro about a softener.
What you can do
A water softener is the system built for hardness; for an ion exchange softener, look for NSF/ANSI 44. Read water softeners in Phoenix for how to size one to these figures, and whole-house water softeners for treating every tap. The city’s report points readers to the Water Quality Association, wqa.org, for information on home treatment systems.
Testing your own tap
The city’s range is wide, from 10 to 17.6 grains per gallon. Your tap may be anywhere in it. A hardness test at your kitchen tap gives the figure that matters for your home, and it is the figure a softener should be set to. If you already have a softener, test before and after it to see whether it is doing its job. See water testing in Phoenix for how to go about it.
Scale, soap and cleaning
Living with hard water is mostly a cleaning job. Scale builds on fixtures and inside the water heater, and soap scum forms where soap meets calcium. Cleaning deals with the surface; a softener deals with the cause. Which you choose depends on how much the scale bothers you.
Hard water and Arizona
People also search for Arizona hard water as a whole. This site gives hardness figures only from a utility’s own report, for that utility’s customers, because vendor pages publish city numbers that disagree with each other. For Phoenix, that is the City of Phoenix 2025 report. For anywhere else in Arizona, ask the water provider on your bill.
Not on City of Phoenix water?
If your water comes from another provider, the city’s figures are not yours. Ask your provider for its annual water quality report and use its hardness figure. The areas page lists Valley cities this site covers.
Questions people ask
How hard is Phoenix, AZ water?
172 to 302 ppm, or 10 to 17.6 grains per gallon, in the City of Phoenix 2025 report.
Why is Phoenix water so hard?
The city’s 2025 report says the calcium and magnesium come from the soils the source water contacts as it travels to Phoenix’s treatment plants, and are leached into the water. Phoenix draws on the Salt, Verde and Colorado rivers and some groundwater.
Ask a local pro