6 Things You Should Never Put on the Bottom Rack of Your Dishwasher

While having a dishwasher in your kitchen is certainly ultra convenient on a day-to-day basis, not all commonly used cooking items are meant to be cleaned this way—or at least do not belong on the dishwasher’s bottom rack. To ensure the longevity of your go-to cooking tools, we’ve spoken with three cleaning experts and asked them to share a handful of kitchen items that will suffer if placed on the bottom dish rack.

Here, our experts provide input on the best way to clean these items so they’ll last for years to come, whether that means placing them on the dishwasher’s top rack or hand washing them.

Plastic Containers and Lids

Tupperware is meant to last you for years on end, and you’d like to use your plastic pieces time and time again, be sure not to place them on the bottom rack of the dishwasher.

“Even if they’re labeled dishwasher-safe, plastic can warp or melt on the bottom rack where the heat is most intense,” Robin Murphy, the founder of Maid Brigade, says.

Always be sure to clean these items on the top rack, where they’ll be safe.

Plastic Cutting Boards

Speaking of plastic items, be sure not to place plastic cutting boards on the bottom dish rack either, Steve Evans, the owner of Memphis Maids, adds.

“They also warp as well with excessive heat, and you want to make sure your cutting boards are sturdy and straight,” he says.

Normally use wooden cutting boards? These don’t belong in the dishwasher under any circumstances, Evans adds.

Silicone Bakeware and Utensils

The next time you finish baking something sweet, take the time to properly clean your silicone bakeware and utensils—which means making sure to not place them on the bottom dishrack.

“Even though silicone can take oven heat, dishwasher detergent is a different beast; it breaks down the nonstick surface and can leave a chalky residue,” Murphy says.

While she recommends handwashing silicone items if possible, you can also place them on the top rack of the dishwasher if absolutely necessary. Murphy explains how the top rack gets more of a gentle mist, while the bottom rack is more like a pressure washer.

Measuring Cups and Spoons

When using a measuring cup or spoon, it’s important to be able to read the printed measurements on the side in order to perfect your recipe. However, as Murphy explains, these numbers will often fade when placed inside the dishwasher.

She suggests placing them in the top rack instead, noting that if you really want to be safe, handwashing these items is the way to go. It’s worth spending a little extra time and effort cleaning these so that they will continue to serve you well in the future.

Insulated Mugs and Tumblers

These days, most people own at least a few reusable mugs and tumblers that they rely on frequently. It’s important to clean your favorite mugs and tumblers on a regular basis, but if you’re using vessels that are designed specifically to keep your drinks hot or cool all day long, the dishwasher isn’t going to be your best friend.

When exposed to the heat from the dishwasher, the vacuum seal that keeps your drinks hot or cold can become damaged, Murphy explains, adding that water and steam can also affect these types of cups’ insulation permanently.

“It’s one of those things that looks fine until it isn’t,” she says. “Hand wash to play it safe.”

Sharp Knives

It’s best to avoid placing sharp knives on the bottom dish rack for a couple of different reasons, Claudia Meneses, the CEO and founder of Avanti Green Eco Cleaning, explains. For one, she notes, the blades can dull more quickly when knives are on the bottom rack. Secondly, she points out, this placement makes it all too easy to accidentally cut yourself when removing a knife from the dishwasher.

Source: The Spruce
This article was originally published by The Spruce on May 10, 2025.
6 Things You Should Never Put on the Bottom Rack of Your Dishwasher