Why Is There White Buildup on My Faucets? (And How to Stop It)

If you live in the Phoenix area, you have almost certainly seen it: a chalky white crust around the base of the kitchen faucet, clogging the showerhead or fogging up the shower door. You scrub it off, and a few weeks later it is back. Here is what that buildup actually is, how to remove it without damaging your fixtures, and what it takes to stop it at the source.

What the white buildup is

The deposit is mineral scale, often called limescale. Hard water carries dissolved minerals, mainly calcium and magnesium. When a drop of water evaporates or is heated, the water leaves but the minerals stay behind, mostly as calcium carbonate. Layer by layer, those minerals build into the crust you see.

Scale is not dirt and it is not a sign that your home is unclean. It is simply the mineral content of your water becoming visible wherever water repeatedly dries.

Why it shows up so much in Arizona homes

Two things combine here. First, much of central Arizona's municipal water is commonly described as hard to very hard, because it travels long distances through mineral-rich rock and soil. Second, the desert climate dries water quickly, so deposits form faster and more often than in humid regions. Your city's annual water quality report lists the measured hardness for your area.

Where it tends to form

• Faucet aerators and the base of faucets, where drips collect and dry.
• Showerheads, where mineral deposits can block spray holes.
• Glass shower doors and tile, as cloudy film and spots.
• Dishwashers, kettles and coffee makers, where water is heated.
• Inside water heaters and pipes, where you cannot see it.

How to remove it safely

Scale is alkaline, so a mild acid dissolves it. Plain white vinegar is the usual household choice.

1. 1Unscrew the faucet aerator or showerhead if you can, and soak it in white vinegar for 30 to 60 minutes. For a fixed showerhead, fill a bag with vinegar and secure it around the head.
2. 2For deposits on the fixture itself, lay a vinegar-soaked cloth over the area and let it sit, then wipe with a soft cloth. A soft toothbrush helps in crevices.
3. 3Rinse thoroughly and dry the surface so new deposits do not form right away.
4. 4Check the manufacturer's care guidance for special finishes such as brushed nickel, oil-rubbed bronze or matte black. Some finishes should not sit in vinegar for long, and abrasive pads can scratch almost any finish.

Why it always comes back

Cleaning removes the deposit, not the minerals in the water. As long as hard water flows through the fixture, every drop that dries adds another trace of scale. That is why buildup returns on the same schedule no matter which cleaner you use.

How to stop it at the source

A water softener addresses hardness before the water reaches your fixtures. Most residential softeners use ion exchange: water passes through a bed of resin beads that swap calcium and magnesium for sodium or potassium ions. With the hardness minerals reduced, there is far less left behind when water dries, so faucets, showerheads and glass stay cleaner between normal cleanings, and appliances are exposed to less scale.

Two things a softener does not do: it does not change chlorine taste or odor, and it is not a drinking-water filter. Homes that also want better-tasting drinking water often pair a softener with a reverse osmosis system at the kitchen sink, and homes with chlorine odor throughout the house may add whole-home filtration.

The scale you cannot see

The buildup on your faucet is the visible tip. The same deposits form inside water heaters, dishwashers, washing machines and the pipes that feed them. Scale acts as an insulating layer in a water heater, which means the heater has to work harder to warm the water. Appliance manufacturers generally recommend periodic descaling in hard-water areas for this reason. Treating hardness at the point of entry protects the equipment you cannot easily inspect.

Not sure how hard your water is?

Start with your utility's water quality report, or request a free water assessment and we will test at your tap and walk through the options that fit your home.