Water Hardness in Phoenix and the Valley, by City, Provider and Neighborhood

Valley tap water is some of the hardest in the country, but how hard depends on who supplies your home and where that water comes from. This page lists the hardness each water provider itself reports, for 19 cities, districts and zones, with a link to every source. Figures are the most recent each provider had published as of September 2026.

They are the most recent figures each provider had published when we checked in September 2026. Most come from the 2025 water quality reports released in mid 2026. A few providers have not printed a hardness figure for a year or more, so the data year column shows how old each one is. Providers publish new reports each summer, and we recheck this page when they do.

The Water Quality Association scale is the one most softener makers use: under 1 grain per gallon is soft, 1 to 3.5 is slightly hard, 3.5 to 7 is moderately hard, 7 to 10.5 is hard, and anything over 10.5 is very hard. Almost every figure on this page lands in the very hard band. One grain per gallon equals 17.1 milligrams per liter.

Because most Valley cities blend several sources, and the blend changes by season and by where you live. Salt and Verde river water is the softest of the three main supplies, Colorado River water is harder, and groundwater varies well by well from quite soft to extremely hard. A home near a well field can see very different water from one across town.

No. Hardness is calcium and magnesium, and it is not regulated as a health concern. Every provider on this page says so in its own report. The cost of hard water is to plumbing and appliances: scale in water heaters, stuck valves, clogged aerators and shower heads, spotted glass and shorter appliance life.

Most manufacturers call for a descaling flush about once a year and more often in very hard water, and they can deny a heat exchanger warranty claim when scale is the cause. With the numbers on this page, yearly is the minimum in most of the Valley unless the home has a softener ahead of the heater. Check your unit's manual for its exact schedule.

Yes. Reverse osmosis membranes foul with scale when fed very hard water, which cuts their output and their life. A softener ahead of the system, or at least regular filter and membrane changes on the maker's schedule, keeps it working. Many Valley homes pair a whole home softener with a reverse osmosis tap at the kitchen sink for that reason.

Cave Creek's water system report lists calcium and total dissolved solids but not hardness. The City of Buckeye does not print a hardness figure in its water quality report or on its water pages. The report says only that the city relies almost entirely on groundwater and that dissolved minerals affect taste and hardness. We do not print numbers from water treatment sales sites, so both are left blank. A simple test strip or a free in home test will give you your own figure.

Each figure was read from the provider's own annual water quality report or its own water quality web page, and the source link is in the table. Where a provider prints only grains per gallon, we converted to milligrams per liter by multiplying by 17.1 and marked it as converted. Where the newest report prints no hardness figure, we used the most recent official document that does and show its year.