Phoenix Hard Water: What Homeowners Should Know

Ask almost anyone who has moved to the Valley and they will mention the water: spots on the dishes, crust on the faucets, skin that feels dry after a shower. This guide explains where Phoenix-area water comes from, why it is hard, how to read the numbers and what you can realistically do about it.

Where the Valley's water comes from

Cities across metro Phoenix draw on a mix of sources: surface water from the Salt and Verde rivers delivered through the Salt River Project, Colorado River water delivered through the Central Arizona Project canal, and groundwater pumped from local aquifers. The exact blend varies by city and shifts through the year, which is one reason hardness can differ between neighbouring communities and even between seasons.

Why the water is hard

Hardness is a measure of dissolved calcium and magnesium. Water picks up these minerals as it moves across and through rock and soil, and the rivers and aquifers that supply Arizona pass through a great deal of mineral-rich geology. By the time it reaches a treatment plant, the water carries a significant dissolved mineral load. Municipal treatment makes the water safe to drink, but softening is generally not part of that process.

How hardness is measured

Hardness is reported either in milligrams per liter (mg/L, equivalent to parts per million) or in grains per gallon (gpg). One grain per gallon equals about 17.1 mg/L. The U.S. Geological Survey uses these general bands:

Water across much of the Phoenix metro is commonly described as hard to very hard on this scale. We deliberately do not quote a single number here, because it varies by city, source blend and time of year. The most reliable figure for your home is the hardness listed in your city's annual water quality report, sometimes called a consumer confidence report, or a test taken at your own tap.

Is hard water safe?

Hardness itself is not regulated as a health contaminant. Calcium and magnesium are minerals people consume in food every day. The concerns with hard water are practical and cosmetic: scale on fixtures and inside appliances, spotting on glass, soap that does not lather well and the way water feels on skin and hair.

What hard water does around the house

• Leaves white mineral deposits on faucets, showerheads, tile and glass.
• Builds scale inside water heaters, dishwashers, washing machines and coffee makers, which can affect efficiency and lifespan.
• Reacts with soap to form soap scum, so you tend to use more soap, shampoo and detergent.
• Leaves a film on skin and hair that many people describe as dry or dull.
• Causes cloudy ice and spotting on glassware, even straight out of the dishwasher.

Hardness versus taste

People often lump every water complaint together, but hardness and taste are mostly separate issues. Hardness drives scale and spotting. Taste and odor in drinking water usually come from disinfectants such as chlorine or chloramine, which utilities add to keep water safe in the distribution system, and from the overall level of dissolved solids. That distinction matters when choosing treatment, because a softener does not change taste and a drinking-water filter does not stop scale.

Your treatment options

• A water softener reduces hardness for the whole home through ion exchange. It is the system that targets scale, spotting and the feel of the water.
• A reverse osmosis system treats drinking and cooking water at a dedicated kitchen tap by pushing water through a semipermeable membrane that reduces dissolved solids.
• Whole-home filtration treats all incoming water, typically with activated carbon for chlorine taste and odor and a sediment stage for particulates. Many homes pair it with a softener.

Find out what is in your water

Pull up your city's water quality report, or request a free water assessment. We test at your tap, explain the results in plain language and only then talk about equipment.