12 Surprising Things That Are Not Dishwasher Safe

I love using the dishwasher. In my house, loading the dishwasher is an art (and sometimes a cause for argument as to whose method is best). In addition to silverware, plates and drinkware, a slew of surprising items clean up nicely in the dishwasher. Unfortunately, this appliance can’t clean everything.

Here’s a quick rundown of some pieces you really shouldn’t put in the dishwasher (and how to clean them instead).

What is not dishwasher safe?

1. Stanley cups

We love staying hydrated, so our Stanley cups get heavy use. But there’s good news and bad news about washing Stanleys. The bad: Stanley cups shouldn’t go in the dishwasher. The heat can damage the finish and—worse—compromise the seal, spoiling the cup’s insulating properties. (Technically, the manual asserts that they can go in the dishwasher, but it’s not ideal.)

The good news, however, is that if you’re using your Stanley cup for water, you don’t have to wash it every day. Just disassemble and give it a quick rinse, then give it a full soap-and-water wash once a week. Use hot water and not too much soap (that’s a surprisingly common dishwashing mistake).

2. Hydro Flask water bottles

You’ll find the same deal with Hydro Flask bottles—the dishwasher puts lots of pressure on the insulated chamber. Older models aren’t dishwasher safe, and while newer bottles technically can go in the dishwasher, it’s not the ideal cleaning method for an insulated cup.

For daily and weekly care, wash your water bottle in hot, soapy water. When it’s time to deep-clean your water bottle (say, if you happen to have forgotten to clean it for a while—we’ve all been there!), fill the bottle with one part white vinegar and five parts water. Let soak overnight, then wash with soapy water, rinse and dry.

3. Cast-iron pans

We love cooking with cast iron, but it does call for special cleanup. Plain cast iron is an uncoated metal, which makes it prone to rust. Putting cast iron in the dishwasher can seriously tarnish the metal. Luckily, it’s easy to clean cast iron. Just wash it in a bit of soapy water, using a gentle cloth or scrubber to dislodge stuck-on particles. Dry it off right away, and rub on a bit of canola oil or other neutral oil to preserve the cooking surface.

4. Wooden kitchen utensils

If you’re trying to divest potentially toxic plastic utensils, wooden tools are a great alternative. They’re soft enough to use on nonstick cookware but sturdy enough to scrape the caramelized coating from a pan. To preserve them, don’t put them in the dishwasher. The intense heat and moisture can make the wood split, warp or crack. Once again, washing in warm, soapy water is the way to go.

5. Sharp knives

We get it, the dishwasher has a handy top rack that’s just right for stowing knives. And a good quality set of knives is sharp and durable—surely they can take it?

Not quite! The long, hot dishwasher cycle wears out knife handles and can blunt the blades, making them less effective and less safe. Another concern is that sharp knives also do damage to the dishwasher rack, potentially poking through the plastic coating.

6. Le Creuset

One of our favorite kitchen tools, Le Creuset cookware is so durable and well-crafted that it can last a lifetime—or even become an heirloom. In order to help it last, it’s important to care for the pots and pans properly. The enameled cast iron is naturally nonstick, making it easy to cook and clean. The simplest cleaning is the best. If the pot is very dirty, soak it for half an hour, then wash with soap and water. Some pots can go into the dishwasher (most pieces without plastic or wooden knobs), but it can dull the enamel, making the pot a bit less pretty.

7. HexClad

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Our favorite HexClad pieces are durable, easy to use and deliver top-notch results. HexClad is nonstick, but it relies on a “seasoning” of coated-on oil to achieve that slick, gliding surface. Sticking the pots and pans into the dishwasher can spoil the seasoning. Worse, the heat can dull the pans, and some detergents can cause etchings or pockmarks on the metal. To keep those pricey pots looking (and cooking) good, wash them with soapy water.

8. Tupperware

It’s tough to beat the performance of old-school Tupperware. But beware: Older Tupperware containers are made from plastic that isn’t dishwasher safe. The high heat of the dishwasher (even the top rack) can warp or misshape the plastic.

9. Nonstick cookware

Nonstick cookware often boasts that it’s dishwasher-safe, likely to lure cooks into the convenience. Unfortunately, as with most types of cookware, nonstick pans don’t thrive in the humid dishwasher, which is rough on nonstick coating.

10. Copper pots and pans

What’s prettier than a shelf full of gleaming copper pots? Expensive, high-quality copper conducts heat like nobody’s business—but it is finicky. Copper definitely doesn’t belong in the dishwasher, which will discolor the copper and can even make it pit. Instead, wash the cookware with soapy water. The same goes for your copper Moscow mule mugs.

11. China

Whether you collect vintage china or received a brand new set for your wedding, it’s best to keep it out of the dishwasher. Most china is made of porcelain, which is actually quite durable. However, the designs painted on the china may wear away in the dishwasher. And any china with metallic accents, such as gold around the rim, should never go in the dishwasher or the microwave.

12. Ceramics

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Found a funky handmade mug at an art fair? Do you collect vintage ceramic bowls? Best to keep them out of the dishwasher. Even though it’s chunky, rustic and sturdy-looking, ceramics can crack in the dishwasher, and will dull with repeated exposure.