Hard water and leaks in Phoenix Valley homes

How hard is your water?

Hardness measures dissolved minerals. The City of Phoenix explains that it comes from minerals such as calcium and magnesium, which the source water picks up from the soil it flows through. Utilities report it in grains per gallon (gpg) or in milligrams per liter. Tempe’s water FAQ gives the conversion: divide milligrams per liter by 17.1 to get grains per gallon.

EPCOR and the City of Avondale both call anything above 10.5 gpg “very hard.” By that scale, most of the Valley qualifies.

These are the figures each utility published, with the report they came from:

A few cautions. Hardness changes with the mix of sources. Mesa’s 2025 report says all of its zones may get groundwater or a blend, and Tempe’s samples ran as high as 33 gpg. Buckeye’s 2024 report gives no hardness figure at all. In Surprise, Goodyear and Buckeye, some addresses are served by a utility other than the city, so check which provider is on your bill.

What scale does in your house

The City of Phoenix’s 2025 water quality report says: “Hard water can cause some types of scaling in pipes and water heaters, and on plumbing fixtures such as faucets and showerheads.” Glendale’s 2024 report says much the same.

The City of Scottsdale’s hard-water fact sheet adds that scale buildup “can reduce the efficiency of some appliances and clog faucets, aerators and, in rare cases, pipes.” It recommends setting water heaters to 120 to 125 degrees.

On faucets and showerheads, scale is mostly a nuisance: white crust, weak spray, clogged aerators. The place where it matters most for water damage is the water heater, because a tank that fails can release a lot of water at once.

Hard water and the water heater

Minerals settle at the bottom of the tank as sediment. The City of Scottsdale’s water heater guide names “overheating from sediment build-up inside the tank” as a main cause of failure. A report written for the Department of Energy by Pacific Northwest National Laboratory (PNNL) says scale “can lead to decreased equipment life” in tankless and gas storage heaters.

The same PNNL report keeps it in proportion. For an electric storage tank, it describes the effect on equipment life as “minimal until sediment covers bottom element (rare),” though it expects the heating element itself to wear out sooner in hard water. Its fix is to drain the tank every year to remove sediment. Scottsdale suggests draining at least 5 gallons every six months where mineral content is high, and warns that the common plastic drain valves can break. The City of Goodyear suggests flushing water heaters once a year.

Our guide to a water heater leaking from the bottom covers what to do when a tank starts to drip.

Softeners: less scale, faster anode wear

A water softener removes most of the hardness, so you get less scale on fixtures and less sediment in the tank. It also changes what you need to watch.

Every tank has an anode rod, a metal rod that corrodes so the steel tank doesn’t. The City of Scottsdale says “softeners can cause the anode to wear out more quickly.” It suggests replacing anodes every 3 to 4 years, and more often if the water is softened. The PNNL report warns that softened water raises the risk of corrosion, which “can decrease equipment life by more than half if not properly mitigated,” and suggests inspecting the anode every 1 to 2 years in soft-water conditions. It explains why: softeners stop scale from forming inside the tank, and that scale can be protective.

The softener itself is a water-using appliance, with supply lines, a drain line and a brine tank. Valley cities flag it as a leak source:

• Constant drain flow. The City of Goodyear lists a softener whose drain line “has water constantly flowing” among the causes of high water use.
• Bad settings. Buckeye warns that softeners “not programmed properly can cycle hundreds of gallons per day.” Goodyear adds that a softener that isn’t set correctly or maintained can damage itself or shorten its own life.
• Routine checks. Mesa lists water softeners among common leak sources, and EPCOR’s reports remind customers to maintain softeners and reverse osmosis units.

Set the softener to your water. Mesa recommends a setting of 16 gpg, and Goodyear suggests 14 to 20 gpg for its city water. A plumber or water treatment technician services the softener itself.

Signs a water heater is near the end

ENERGY STAR lists these warning signs:

• Leaks from joints, seals or seams
• Visible corrosion
• Rust in the water
• Less hot water, caused by sediment
• Rumbling noises from sediment

ENERGY STAR puts the typical life of a storage water heater at about 13 years, and says that if yours may be more than 10 years old, it’s time to consider replacing it before you’re left with an emergency decision. It warns that waiting too long risks “tank rupture and water damage to the floor and carpets.” The City of Scottsdale suggests looking the heater over at least once a month.

How a small leak becomes water damage

Most water damage from a water heater or a softener starts small. A fitting weeps, a valve drips or a supply line seeps at the connection. The water runs down the side of the appliance and spreads where you can’t see it.

• Under cabinets. The Smart Home Water Guide, from the City of Phoenix and the Arizona Municipal Water Users Association, says to check under and around sinks for “wet spots, a musty smell or bowed cabinetry.”
• Into walls. Water wicks up the bottom of drywall. The EPA says wet drywall may be dried in place if it isn’t visibly swollen and the seams are intact. Otherwise it has to be removed and replaced.
• Under flooring. Water runs under carpet pad, laminate and vinyl plank. The EPA says the subfloor under wet flooring must be cleaned and dried too.

The clock matters. The EPA advises drying water-damaged materials within 24 to 48 hours to prevent mold growth, and it lists the inside of walls around leaking pipes among the places mold can hide. Our guide to the signs of hidden mold explains what to watch for.

Slow leaks can also matter for insurance. The Insurance Information Institute says the standard HO-3 policy covers accidental discharge of water from plumbing but excludes seepage. Catching a drip early helps on both counts.

Other leaks to rule out

The sources we checked tie hard water to water heaters, fixtures and scale in pipes. They don’t tie it to slab leaks, and not every leak in a hard-water area has anything to do with minerals.

• Under the slab. The Smart Home Water Guide suggests feeling for warm spots on the floor after running hot water nearby, which could point to a leaking hot water pipe under the concrete. See slab leak water damage.
• A split supply line. A line under a sink or toilet can give way without warning. See burst pipe water damage.
• A leak you can’t find. Turn off every fixture and watch the water meter. The Smart Home Water Guide says that if the sweep hand is moving, you have a continuous leak.

Who does what

A plumber repairs or replaces the water heater, valves and supply lines, and a plumber or water treatment technician services the softener. A restoration provider handles the water damage: removing standing water, drying walls and floors, and taking out materials that can’t be saved. See water heater and appliance leak cleanup.

If a leak soaks anything beyond bare concrete, close the water supply first. Our shut-off valve guide shows where the main valve usually is. Then take photos and call to reach a restoration provider.