8 Things You Should Never Put in the Dishwasher — and Why
Not everything that looks dishwasher-safe can withstand the heat, powerful water jets, and harsh detergent inside a dishwasher. Always check the manufacturer’s care instructions first.
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Wooden utensils and cutting boards — Prolonged exposure to hot water can cause wood to swell, warp, crack, or split. Hand-washing and prompt drying are safer.
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Cast-iron cookware — Dishwasher detergent and prolonged water exposure can strip away seasoning and encourage rust. Wash by hand and dry thoroughly.
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Sharp kitchen knives — Dishwasher detergents and high heat can dull blades, while loose knives can damage racks or pose a handling hazard when unloading.
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Copper cookware — Heat and dishwasher detergent can cause copper to become dull, discolored, or tarnished.
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Delicate crystal or hand-painted glassware — Heat, detergent, and repeated washing can cause clouding, fading, or damage to decorative finishes.
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Nonstick pans with damaged or unverified coatings — Dishwasher exposure can shorten the life of some nonstick finishes. If the manufacturer recommends hand-washing, follow that instruction.
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Insulated travel mugs and vacuum bottles — The dishwasher can damage seals, insulation, or decorative coatings unless the manufacturer specifically labels the item dishwasher-safe.
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Anything labeled “hand wash only” — This is the simplest rule. If the manufacturer specifically says not to use a dishwasher, don’t gamble on it; the item’s materials or construction may not tolerate the conditions.
One useful tip
Don’t assume that “plastic” automatically means dishwasher-safe. Some plastics can warp or degrade in high heat. Look for the manufacturer’s dishwasher-safe symbol or instructions, and place approved plastic items on the appropriate rack.
For expensive, sharp, wooden, or delicate kitchenware, hand-washing is often the safest choice.
