Hard water in Phoenix: what it does to your plumbing

Very hard by any standard. The City of Phoenix 2025 Water Quality Report lists total hardness in the distribution system of 172 to 302 parts per million, or 10 to 17.6 grains per gallon. The report explains that hardness comes from minerals such as calcium and magnesium that the source water picks up from soils on its way to the treatment plants, and that hard water can cause scaling in pipes and water heaters and on fixtures such as faucets and showerheads.

For context, the U.S. Geological Survey's hardness guidelines classify water above 180 milligrams per liter as calcium carbonate as very hard. Most Phoenix tap water is above that line.

Hardness varies because each utility blends different sources. Phoenix says about 97 to 99 percent of its 2025 supply was surface water from the Salt, Verde and Colorado rivers, with about two percent from city wells. Chandler's Water Quality FAQs give a wide range because the city mixes canal water with water from 32 wells. Mesa's 2024 report ties hardness to the zone you live in. Our Scottsdale page covers that city's published ranges by area. For the most accurate number, read your own utility's latest annual report or test your tap.

• Water heaters. Minerals settle as scale on the bottom of a tank and on elements. Chandler's FAQ relays manufacturers' advice to flush a tank every six months without a softener and once a year with one.
• Tankless water heaters. Scale can build up in the heat exchanger, so these units need periodic descaling. See our tank vs tankless guide.
• Faucets and showerheads. White crust on aerators and spray nozzles reduces flow. Soaking them in white vinegar loosens deposits.
• Valves and cartridges. Scale makes shower valves, toilet fill valves and supply stops stiff, and can keep them from sealing.
• Appliances. Dishwashers, washing machines, coffee makers and ice makers lose efficiency as scale builds.

Hard water is not a health problem. The Phoenix report says taste, odor and hardness are not regulated under drinking water health standards and describes them as harmless aesthetic issues.

Not for safety. The city's Water Services FAQ says filters and softeners are typically not necessary unless a physician advises them or you want one as a personal choice, and that if you install one you should follow the manufacturer's maintenance instructions. Whether it pays off depends on how much scale you are willing to manage.

HomeGuide's 2026 national water softener cost guide puts installed costs at:

The same guide lists ongoing costs of $50 to $150 a year for salt or potassium and $100 to $300 or more a year for maintenance. Those are national figures; ask for a local written quote. The Phoenix report adds a caution: failing to follow the manufacturer's operation and maintenance instructions for home treatment systems can result in potentially unsafe water.

Start with your utility's published number. Mesa's report recommends a setting of 16 grains per gallon and then adjusting to preference. If your home has a softener, Chandler's FAQ explains how to put it in bypass mode to check whether it is causing low pressure: find the valve labeled "bypass" and move it in the direction of the arrow.

A softener connects to the main water line, needs a drain for regeneration water and often an electrical outlet. Hire a contractor with an active Arizona license, and check it on the Registrar of Contractors site. Our hiring guide explains which license classes cover plumbing.

We are an independent guide, not a contractor; we do not sell or install equipment. To reach a plumber, call one of the licensed contractors listed on this page or see all listed contractors. Questions about this guide: email us. We do not take service requests.