Top 11+ things you should never put in your dishwasher, according to experts

Some (chef's knife) are obvious, and others (fish and baseball caps?) have experts scratching their heads.

Key Takeaways

• Nonstick pans without a dishwasher-safe label should always be hand-washed.
• Wooden kitchen tools can warp, crack, and breed bacteria in the dishwasher.
• Dishwashers can ruin cast iron by stripping its seasoning and causing rust.

The dishwasher is one of the greatest time-savers and hassle-eliminators to ever enter the kitchen. Having an appliance that takes care of dirty dishes means more time for chilling out after meals. (Cooking is enough hard work!)

Plus, when used properly, dishwashers are more efficient than hand-washing—so using the dishwasher can help you waste less water and save money.

However, that doesn't mean you should put everything in your dishwasher. "There are a number of things you really shouldn't put in your dishwasher," says Larry Ciufo, head of dishwasher testing for Consumer Reports. "The worst of the worst are things that will either harm the item or the machine itself, which you definitely don't want."

Here's a rundown of the biggest dishwasher no-nos. 

1. Nonstick Pans

"If your nonstick pans aren't specifically labeled as dishwasher safe, you should hand-wash them," says Ciufo. "Putting them in the dishwasher will prematurely erode the nonstick coating, and you'll waste money having to replace them sooner than you should have to." 

2. Wooden Cutting Boards or Utensils

Always hand-wash your wooden cutting boards, spoons, and any other wood items you use in the kitchen. "Not only can [wood] warp at high temperatures, but it also swells when wet and can crack, creating an ideal place for bacteria to breed," says Richard Tarrant, senior vice president at Bosch Home Appliances.

3. Cast Iron Cookware

Cast iron pans and griddles are ideal for cooking and browning cornbread, meats, fish, and vegetables, and they're nearly indestructible—unless you put them in the dishwasher. It "will absolutely ruin a perfectly good cast iron pan in a hurry," Ciufo says.

"It can remove the seasoning, which is the baked-on oil that helps prevent food from sticking and guards against rust. You might as well throw the pan out after that." Just remember to gently hand wash your cast iron and it'll last for generations.

4. Crystal

If you have glasses, bowls, or other items made out of crystal, it's best to keep them out of the dishwasher. "Dishwasher detergent and salt can damage the surface and cause glass corrosion," says Tarrant. 

5. Sharp Knives

"Sharp knives are pretty important kitchen tools, and people spend lots of money on a quality set," says Ciufo. "All the more reason not to ruin them by putting them in the dishwasher. It's not a good idea—even if they're labeled as dishwasher safe. Rubbing against other cutlery in the basket can make them dull." Even one washing cycle can damage a knife's blade and cause bluntness, Tarrant adds.

6. Copper

Copper cookware is gorgeous and heats quickly and evenly, but it is expensive, so if you're lucky enough to own copper pots and pans you'll need to coddle them a bit. Tarrant explains that copper needs to be cleaned by hand, because tossing it in the dishwasher can cause it to turn black due to an oxidation process inside the dishwasher. 

7. Pewter, Brass, and Bronze

Like copper, any pewter, brass, or bronze items should be kept out of the dishwasher. "Keep these to handwashing, as they’ll tarnish if not immediately dried," says Tarrant. 

8. Dish Soap

Along with things that should be kept out of the dishwasher so they aren't damaged, there are things that should stay out because they can wreak havoc on the appliance. Dish soap meant for hand-washing dishes is one of these things. "If you run out of detergent, avoid the temptation of using dish soap—it’s too foamy and can damage the appliance," says Tarrant. 

9. Jars With Labels

It's a good idea to clean jars that contained food before recycling or reusing them, but if they have paper labels you're better off washing them by hand than putting them in the dishwasher. That's because the labels can peel off and gum up the wash system, and also stick to everything else in the same load.

10. Fish, Potatoes, and Any Other Food

You might have seen social media posts about using the dishwasher to cook fish or wash potatoes. Don't do it. Not only is it gross, but it could also be unsafe—the dishwasher might not be consistently hot enough to cook fish to a safe internal temperature. Plus, it could deposit old food and soap residue on your food.

11. Clothes, Household Items, Electronics, and Car Parts

Bras, computer keyboards, car parts, plastic shoes, baseball caps, and gardening tools are just a few of the odd things people have been known to put in their dishwashers, according to Consumer Reports. Any of these items can be damaged by the dishwasher, cause damage to the dishwasher, or both, so unless an item is specifically labeled as dishwasher safe, keep it out of the appliance—no matter what the influencers on TikTok say.