13 Common Kitchen Items You Shouldn't Put In The Dishwasher

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Dishwashers are a household essential for many. They make it easier to wash dishes in bulk and eliminate most of the manual labor involved. It may be tempting to throw all of your dishes in the dishwasher after cooking and eating, but you and your family should be discriminating about what you place inside.

The short answer is that not all items are dishwasher-friendly, and tossing certain materials and items into them can damage your dishes and kitchenware. This goes for expensive items like fine china as well as cheap plastics, such as disposable plates and forks. There are many reasons why dishwashers are too extreme for these items, primarily due to the high heat, excessive water, and the intense water pressure that's scouring the dishes inside, which can cause warping, fractures, and other detrimental issues. Dishwasher soap is also formulated differently from typical dish soap and can be harsher, potentially damaging fragile dishes, which creates a whole other issue since dish soap isn't recommended as a dishwasher cleaning agent. For these and other reasons, here are the items you should avoid putting in your dishwasher, except under special circumstances.

It may be tempting to stack wooden cutting boards in a dishwasher, especially if they're too large and bulky to wash in a kitchen sink. However, putting wooden kitchenware in the dishwasher is a bad idea. The high heat and excessive moisture gradually degrade wood materials, causing warping and splintering that will ruin the cutting board's appearance and diminish its quality.

Instead of tucking wood boards in a dishwasher, hand-wash them using minimal water. You don't have to worry as much about spilling water everywhere, since they shouldn't be fully submerged. Wipe down the boards to avoid oversaturating them with moisture, and if they're too dirty to solely clean with water, use other common household products. Baking soda removes stains, vinegar disinfects surfaces, and coarse salt and lemon help with general cleaning. When the cleaning is over with, lean the boards against a wall to dry to ensure the bottom, sides, and top don't harbor bacteria or mold.

When the time comes to wash your hand-painted or metal-trimmed ceramics, it's vital you take a gentle approach. Your dishwasher will not be gentle, and the only way to guarantee that your fine china, vintage dishes, and mugs stay safe is by keeping them outside of this appliance. The high water pressure causes hand-painted images and designs to fade,  and the high temperatures and chemical-laden detergents can even rub away the intricate designs.

Some hand-painted mugs and plates may claim to be dishwasher-safe, since they're fired at higher temperatures and have a stoneware glaze covering their delicate art. The glaze may make the dishes more resistant to the temperature, water, and detergent swirling around in the dishwasher, but it can't protect them from other items inside the dishwasher. When a cycle is running and a dishwasher is scouring its contents, things can get knocked around and potentially slam into your beloved ceramics. This can chip or shatter them, causing irreparable damage. Given this risk, the best course of action is to handwash using dish soap and a sponge.

If you're a routine user of disposable plastic plates and utensils, occasionally reusing them seems like a good idea to save the environment and money. However, they typically cannot be conveniently washed in a dishwasher, since flimsy plastic utensils and plates melt and deform in high-temperature washes. On an even scarier note, high heat can cause plastics to release harmful chemicals, like BPA. And even "BPA-free"-labeled plastics aren't always as safe as they seem; they may still contain other chemicals that are similar to BPA.

Fortunately, some plastics are dishwasher-safe and are marked accordingly. If you can't find a "dishwasher-safe" engraving or sticker, look at the other codes etched in the bottom. Disposable plates often have the number one etched on the bottom, which indicates they are recyclable and are intended to be single-use. In other words, they're too flimsy to withstand a dishwashing cycle.

The safest approach with questionable plastic kitchen items is to hand-wash them. If you do load your verified-safe plastic items in the dishwasher, always use the top rack. Don't put your dishwasher on the deep clean or sanitizing cycle, which are more likely to deform the plastic.

Don't fall for the misconception that metal is guaranteed to be resilient. Copper pans, pots, and mugs are popular kitchen items for enthusiastic chefs and mixologists, but they aren't as strong as other metal materials. In fact, copper is relatively soft compared to other metals. It scratches easily, especially if it comes in contact with other hard items. Abrasive detergents can also dull the surface and lead to tarnish around the copper exterior.

Given these characteristics, opt to hand-wash your copperware with sudsy water rather than using the dishwasher. In fact, you should also wash and rinse copper items with soapy water after using a chemical cleaner or polish, as giving them a quick wash and rinse slows future tarnish buildup. There's also a decades-old cleaning hack to make copper kitchen items shine like new, which uses common household ingredients like lemon and cream of tartar.

Iron isn't as soft as copper, but there are still good reasons to avoid putting heavy-duty cast-iron pans in dishwashers. Part of cast-iron cookware's appeal is that it retains a seasoning from past cooking ventures. If you put it in your dishwasher, that seasoning is removed, taking away the key feature of this traditional cookware material and its non-stick ability. Dishwashers can also cause rust to form, which cast iron is particularly susceptible to.

There are some instances when you can put a cast-iron pan in the dishwasher. Heat-treated cookware is marked dishwasher-safe, such as the Kana Lifestyle Store Milo by Kana 10-Inch Enameled Cast Iron Skillet, but items without these labels must be hand-washed to protect the seasoned, non-stick surface. Use a small amount of soap, and do not soak the pan while hand-washing. If there's hardened residue that you can't get off, be careful not to scratch your pan. There are tools designed for scraping food without damaging the metal, such as the Matscover Store Pan Scraper.

There are few items as frustrating to clean as cheese graters and produce peelers. These tools often have divots and a mix of plastic and metal pieces, which makes them difficult to clean by hand. As time-consuming as it is, you should clean them by hand anyway, and skip the dishwasher. Not only can dishwasher detergent's harsh chemicals dull the metal blades on these tools, but the high temperatures can also loosen the handles, causing these items to eventually fall apart after one too many washes. Even dishwasher-safe tools won't last as long as they would with regular hand-washing.

If your cheese grater or produce peeler is labeled dishwasher-safe, it may be more resilient against the high temperatures and harsh detergents. However, this still isn't the best way to wash them. Dishwashers don't have minds of their own, and they can't detect and target stubborn pieces of food hidden in grater and peeler crevices. The dishwasher dry cycle can also bake remaining food residue into the tool, making it even harder to clean it afterward.

The easiest answer is to avoid putting these items in a dishwasher altogether. Soak them in warm, soapy water, then use a stiff brush to get crumbs and leftover pieces out of the hard-to-reach places. The sooner you clean them, the better, so don't hesitate to start soaking as soon as you're done food prepping. If your grater or peeler is labeled dishwasher-safe and you insist on using a dishwasher, at least skip the dry cycle to avoid baking on any residue.

Whether you're washing an empty sauce container or have cute stickers plastered to your tumbler, keep in mind that labels tend not to be dishwasher-friendly. Many labels break down in the heat and get stuck to the dishwasher interior or to other dishes, which can create a whole mess that's even more tedious to clean up than traditional hand-washing.

Fortunately, it's easy to remove stickers from glass jars using a quick solution. As long as labels are peeled off beforehand, most glass jars and other items are perfectly safe to put in the dishwasher (though you should take proper precautions depending on the type and thickness of the glass). On a positive note, you don't always have to forgo stickers on dishes, reusable bottles, and food containers, since there are stickers designed to be dishwasher-safe. There are plain white multipurpose labels like Avery No-Iron Fabric Labels, and more colorful options like the PreFeel Assorted Colors Waterproof Removable Labels. These are a practical solution if you want a perfectly organized kitchen with many labeled containers.

Facing the task of cleaning spice mills and coffee grinders, with all their metallic and plastic parts, may cause the same sense of dread as cheese graters and produce peelers. The metal gears in particular are tricky to clear out, and they're also the primary reason why you shouldn't place these tools in a dishwasher. Putting metal gears in such a hot and humid environment can cause rusting, which in turn can ruin the tool.

Many brands recommend not putting their tools in the dishwasher. However, there are some models of spice mills and coffee grinders that are partially machine-washable. Tools like the IKEA 365+ IHÄRDIG Spice Mill have removable parts that are safe to put in the top level of the dishwasher. However, most other brands don't recommend it at all, so instead, use a stiff brush and warm water to clean your grinders and mills. The best course of action is always to follow the manufacturer's instructions, as products' instructions can greatly differ, especially since they range from manual to electronically-powered.

Carrying around a reusable water bottle or tumbler isn't just trendy, it's also more fiscally responsible and healthier. However, water bottles need regular cleaning to keep bacteria at bay. Most water bottles are better off being washed by hand, since dishwasher detergent can be abrasive and may slowly damage the seals and pieces. Dishwashers also don't clean as thoroughly as you may think. Due to the unique cylindrical shape of water bottles, dishwashers struggle to clean the inside, mouthpiece, and rubber seals. 

Like most modern kitchen tools, there are dishwasher-safe water bottles and tumblers. Stanleys and newer Hydro Flasks are generally dishwasher-safe, and other brands are too, but make sure the manufacturer specifies this before using a dishwasher to clean them. Even if a bottle is advertised as dishwasher safe, mold can still get trapped in hidden places, and while a dishwasher's sanitize cycle may help keep said mold at bay, such a harsh dishwashing cycle can also damage the bottle.

Mechanical dishwashers have been around since the 19th century, but that doesn't make them safe for vintage kitchen items. Vintage and antique milk glasses made by certain manufacturers are very valuable, and you shouldn't pass up on these glass items if you see them at a thrift store. If you own an expensive piece, it's vital to keep it preserved to retain value, and these vintage glasswares should never be put in the dishwasher. Doing so slowly discolors the glass, most commonly with an unappealing yellow tint. The classic dishwasher combination of high heat and polishing detergent also wears down the finish and makes the glass more vulnerable to damage.

The gentlest way to care for vintage milk glasses is to wash them by hand; soapy water and a soft sponge are all that's necessary. Keeping these vintage items out of the dishwasher also ensures the delicate milk glasses aren't damaged by jostled items. 

Pressure cookers, rice cookers, and slow cookers make cooking easy. They eliminate the need for many pots and pans while preparing food, which already means there are fewer dishes to clean. As tempting as it is to make the cooking process even easier by tossing their lids in a dishwasher, be wary of the downsides. When lids lined with rubber gaskets are thrown in the whirlpool of a dishwasher, small food particles and detergent can get lodged in the regulator, safety valves, and vents. It should also go without saying that other pieces of your pressure cooker shouldn't be put in the dishwasher, especially the electronic base.

Although popular brands like Russell Hobbs and Lakeland aren't dishwasher safe, Instant Pot is, as long as you follow their strict instructions. They recommend only putting the lid on the top rack, and after removing the valve and seal attachments. You should also check the seals after a deep clean to make sure nothing is stuck inside. 

Instead, you can clean an Instant Pot without damaging it – or indeed any pressure cooker — by washing it with warm and soapy water. Take apart the components as directed to ensure each piece is cleaned thoroughly. To further preserve your pressure cooker, make sure you store the lid separately from the pot. When these pieces are left together for too long, they can permanently seal together and render the device unusable.

Don't overestimate the resilience of natural stone kitchen items. Your pizza stone, mortar and pestle, or solid granite cutting board may seem impervious to damage, but like many other kitchen items, they're very vulnerable to high heat and abrasive dishwasher detergents. Exposure to these elements dulls their finishes and can even cause cracks and fractures in the material.

Unless the stone is approved for occasional dishwasher use by the manufacturer, the best cleaning method depends on the type of stone in question. Natural stone, like granite or volcanic rock, should primarily be cleaned with water and a brush. A little soap is fine, but you should limit your use as you would with a cast-iron pan, as recommended by popular pizza stone brands like Skotti. Marble is usually more resilient, meaning you can use soap safely, and it's also occasionally dishwasher-safe. Typically, dishwasher-safe stone items will be made of a non-porous stone and have a glaze, but the better option is to handwash them. However it's cleaned, ensure any stone dish or tool is completely dry before putting it away.

Kitchen knives are one of the most common kitchen essentials, but before you toss this valuable tool in your dishwasher, know the risks in doing so. Exposure to dishwasher detergents, which lean towards alkaline and abrasive properties, can cause metal blades to corrode. The cutting edge will also dull much faster than if the knives were simply done by hand, requiring more rounds of sharpening. 

While a dull blade is an easy fix, knives face another risk in dishwashers. The glue binding the handles and blades together can disintegrate, especially if the handles are hollow. If the glue dissolves, the two pieces will detach, and you may need to replace the knife. Putting knives in a dishwasher also puts the machine itself at risk. During an extreme wash cycle, they can nick the interior dishwasher coating, which can cause the inside of a dishwasher to rust over time.

Despite what you may have been told, do not use vinegar to clean your kitchen knives, for this is just as detrimental as washing knives in the dishwasher. Carefully handwash each knife with soapy water, being careful not to pile them atop one another in the sink, and put them out to dry with the handle up (if you have a utensil rack). The less they nick one another, your sink, and other dishes, the less they'll dull and cause unintentional damage.