How to Prevent Rust in a Dishwasher: Tips and Coatings

Where rust appears first

Rust in a dishwasher nearly always starts at the same few places: the coated edges of the upper and lower racks, the tips of the tines that hold plates and glasses, the bottom of the tub around the drain, and the inner face of the door where the gasket traps moisture. These are the spots that take the most abrasion and stay wet the longest, so the protective finish wears through there first.

The material matters too. Many racks are made of steel wire wrapped in a polymer coating that can chip when a pot or a knife edge strikes it. Tubs come in plastic, porcelain-coated steel, and stainless steel. A stainless steel tub resists corrosion far better than a coated steel one, but the door liner and the rack coating are where you will see the first orange spots regardless of tub material. For a closer look at how rack finishes differ, see our article on rack coating materials.

Why dishwasher metal corrodes

Corrosion needs three things: exposed metal, water, and heat. A dishwasher provides all three on every cycle. The machine heats the wash water, and ENERGY STAR notes that certified models boost water temperatures to 140 degrees Fahrenheit for improved cleaning and disinfection. That heat, combined with detergent chemistry and the salts dissolved in most tap water, attacks any spot where the protective coating is gone.

Mineral content in the water plays a supporting role. The water that reaches a home is treated to be safe to drink, but it still carries dissolved minerals that dry onto racks and tub surfaces and trap moisture against bare metal. Keeping surfaces free of dried-on deposits is one of the simplest ways to slow the process.

Protecting rack edges and tines

When a chip does appear, the metal beneath is exposed and will not heal on its own. A rack coating repair kit seals the bare spot if you apply it before the corrosion spreads. If rust has already taken hold, see our guide on removing rust from dishwasher racks.

• Point sharp items down. Knives, forks, and utensils with thin metal edges should load with the points down, so the sharp edges do not scrape the rack coating when you slide the rack in and out.
• Do not overstuff the rack. When items press hard against the tines or the rack edge, the polymer coating wears thin at those contact points.
• Inspect after heavy loads. A dropped cast-iron pan or a roasting pan with a rough edge can chip a rack tine. Catch the chip early and touch it up.
• Keep bare metal off the coating. Do not let the metal feet of small appliances sit directly on the rack, and avoid wire baskets that abrade the tines.

Caring for the tub and door

The tub and the inner door see less abrasion than the racks, but they still corrode when the finish is damaged. On a porcelain-coated steel tub, a dropped dish or a fallen rack wheel can knock chips out of the enamel, and water works into those chips. Stainless steel resists rust much better, but it is not immune: abrasive pads, chlorine-based cleaners, and metal tools can scratch the surface and leave stains or pitting.

Clean the interior with a soft cloth or sponge and a cleaner suited to the surface. If you have a stainless steel tub, follow the same care you would give a stainless sink, and clean it without abrasive scouring. Wipe the door gasket dry after the last load of the day, and make sure the vent area is not blocked. A gasket that stays wet and tightly sealed is one of the most common causes of corrosion on the tub rim and the door liner.

Daily habits that slow corrosion

The ENERGY STAR test method assumes a dishwasher runs about 215 cycles per year in the average home. Over that many cycles, small habits add up: every load heats, soaks, and dries the rack coating and tub surface again. Keeping the interior dry and free of food debris between runs is the cheapest corrosion protection you have.

• Scrape food off instead of rinsing. ENERGY STAR points out that rinsing increases total water and energy use and that today's detergents are designed to handle food left on the plate. Scraping also removes corrosive food acids rather than letting them sit in the wash water.
• Run full loads. A dishwasher uses about the same energy and water regardless of how many dishes are inside, and fuller loads mean fewer cycles and less time with a damp interior.
• Use the rinse hold if dishes will sit overnight. ENERGY STAR notes that the rinse feature uses a fraction of the water of hand rinsing and keeps food from drying onto the racks.
• Let the interior dry out between cycles. Leave the door cracked for a few minutes after a cycle so the racks and tub dry instead of staying wet.

When to touch up and when to replace

As a general rule, small chips on rack edges and tine tips, and light surface rust on the tub, are worth a touch-up if the rest of the dishwasher is in good shape. Widespread rust, flaking coating, or corrosion that has eaten through the tub or weakened a rack is not. A rack with a few rusted tines can sometimes be replaced as a part, but a tub that has rusted through usually means the whole unit needs to go.

When you shop for a replacement, prioritize a stainless steel tub and racks with a durable coating. The best built-in dishwashers guide is a good starting point, and you can narrow by finish with the best stainless steel dishwashers roundup. If you live with a compact model, the best countertop dishwashers list shows options where rack care is simpler because the loads are smaller.

What to pick for your use

Questions

Can rust be removed from a dishwasher rack?

Light rust can be scrubbed back to bare metal with a fine abrasive and then sealed with a food-safe appliance touch-up coating. If the coating is flaking on many tines or the steel underneath is weakened, replace the rack instead. See the steps in our rack rust removal guide.

Does a stainless steel tub rust?

Stainless steel resists corrosion but can develop stains or pitting if scratched with abrasive pads or exposed to chlorine-based cleaners. Genuine rust through the tub wall is rare and usually points to long-term neglect or a manufacturing defect.

Is a rusty rack safe for dishes?

Small rust spots are not a health hazard, but rust flakes can transfer to plates and stain them. Seal any chip or spot early so the rust does not spread to the dishes.

What causes rust around the rack tine tips?

Tine tips are the thinnest part of the polymer coating and the first surface chipped during loading and unloading. Once the metal is exposed, heat and moisture do the rest. Coatings applied thickly at the factory take longer to wear through.

Does hard water cause rust in a dishwasher?

Hard water does not corrode steel directly, but the mineral scale it leaves can trap moisture against exposed metal and hide early rust. Cleaning the interior regularly to remove scale and keeping racks dry between cycles slows the problem.