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7 Things You Should Never Put In Your Dishwasher, Even Some Items Labeled Dishwasher Safe

November 5, 202639Views

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The dishwasher feels like a miracle machine. You load it, press a button, and walk away.

But Consumer Reports, the nonprofit product-testing organization, has published lists of things that should never go in the machine, and some are items many of us have loaded for years. The advice below comes from a Consumer Reports segment on News4JAX dated August 13, 2018, and a 6abc Philadelphia report on a newer Consumer Reports list from October 11, 2023.

The dishwasher is a hard worker, but it uses hot water and strong detergent, and not every material can handle that over time.

Here are 7 things from those lists, with the reason and the expert or company Consumer Reports cited. Check your own manual too, since models differ.

Cast Iron Cookware Can Lose Its Seasoning And Turn Rusty

Consumer Reports says the dishwasher can strip the seasoning, which is the baked-on oil that keeps food from sticking and helps prevent rust. The 2018 segment credited Lodge, a cast iron cookware maker, for that information.

The 2023 advice is to wipe the pan with water and a paper towel, adding a little dish soap only if food is stuck on. It takes about a minute, and it protects a pan that can last for decades.

Nonstick Pans Can Wear Out Even When The Label Says Dishwasher Safe

Here is the surprise. The 2023 list says that even when a pan is labeled dishwasher safe, the combination of detergent and hot water can wear down the nonstick coating over time.

Consumer Reports recommends washing nonstick pans with warm soapy water and a soft sponge or brush. That is a gentler routine that keeps the surface working for longer.

Sharp Knives Can Come Out Dull And Loose At The Handle

Molly Bradley of Consumer Reports said in the 2023 report, “The handles can start to separate over time and they can get knocked around which can dull the blade.”

The 2018 segment adds that rubbing against other cutlery can dull knives, and that hand-washing is better even if they are labeled dishwasher-safe.

Wooden Spoons, Bowls And Cutting Boards Can Warp Or Crack

According to Consumer Reports, wood, water and heat can cause warping or cracking. Both lists include wooden items, from spoons to salad bowls.

A beloved wooden bowl or board is hard to replace, so a quick hand wash is a small price to pay.

For wood that touches raw meat, poultry or seafood, Consumer Reports says to wash with a sponge and hot, soapy water, then disinfect every few months with one tablespoon of chlorine bleach per gallon of water.

Copper, Brass And Aluminum Can Tarnish, Pit Or Dull

Bradley said, “The hot water and harsh detergents can discolor and tarnish copper and aluminum and dull their shine.” Copper pots and Moscow mule cups are on the list, and copper can also get scratched.

The 2018 segment adds brass, bronze and pewter, which high heat and detergent can discolor or pit. Hand-washing with a mild detergent is the advice.

Plastics Not Labeled Dishwasher Safe May Release Chemicals

Consumer Reports’ Don Huber said in the 2018 segment that heat can cause chemicals such as phthalates and BPA to leach from plastic that is not meant for the dishwasher.

If the plastic is labeled safe, the advice is to use the top rack and avoid the sanitize cycle. Plastic containers that have no label at all are best washed by hand.

Insulated Mugs Can Lose Their Ability To Keep Drinks Hot

The 2018 segment says heat and water can damage the vacuum seal in insulated mugs that are not labeled dishwasher-safe. Per LG, that reduces the mug’s ability to keep drinks hot.

Check the bottom of your travel mug for a dishwasher-safe label before loading it. If there is none, hand-washing is the safer choice for a mug you rely on every morning.

The 2018 list ran to 15 items, and a few more are worth knowing. Greasy car or machine parts can clog the wash system, according to Consumer Reports engineer Larry Ciufo, so water cannot circulate to clean your dishes.

Tools used for painting, auto repair or gardening can shorten the dishwasher’s lifespan, according to Electrolux. Bras can cause suds to overflow and the heat may damage the fabric, according to HanesBrands.

Computer keyboards can hold water inside even when the keys look clean. Jars with labels can clog the wash system when the labels come unglued, according to Kenmore, and china with gold leaf can discolor or fade.

Fish cooked in the dishwasher is on the list too, because manufacturers do not recommend it. LG said water temperature is not as consistent in a dishwasher as on a stove, so pathogens like Salmonella may not be killed. Potatoes can come out unclean because of residual soap and rinse aid, so rinse them in the sink instead.

Consumer Reports adds a plain reminder from its 2023 list: food should never go in the dishwasher, regardless of what you see on TikTok. When in doubt, read the care instructions that came with the item and your dishwasher. A few minutes at the sink can keep a favorite pan, knife or mug going for many more years.