The One Thing You Should Never Put on the Bottom Dishwasher Rack

The internet is ablaze with debates on the “right” way to load a dishwasher. Should silverware face up or down? Do you need to rinse dishes first, or is that a waste of time? Should you squeeze everything in or leave a little room? Marriages, families, and friendships have been tested by these conundrums, and here’s one more to add to the list: Is it really a problem if you load plastic containers on the bottom rack?

To settle this, I spoke with Marty Olsen, Part Leader, Quality Engineering at LG Electronics, to uncover exactly why you should never put plastic containers on the bottom rack of your dishwasher.

Why Plastic Doesn’t Belong on the Bottom Rack

If you’ve ever tried microwaving a plastic toy (Barbie, perhaps?) in your childhood, you already have a preview of what happens when plastic meets heat. Most dishwashers have an exposed heating element at the bottom, designed to heat water and dry the dishes. If plastic falls there, it can melt or warp. This is especially true of takeout containers or any plastic used for pre-packaged food which should never be put in the dishwasher. 

Olsen says, “Heat is most stressful on plastics in the bottom rack when an exposed heating element is the main source of drying heat. If plastic items come in contact with the element during a dry cycle, it will most likely incur damage to the utensil. This can happen when consumers lay items in the lower rack instead of a middle rack or third rack if the dishwasher is equipped.”

How To Load Plastic in the Dishwasher

The safest place for plastic containers is on the top rack, farthest from the heating element. Here are a few tips to ensure they come out clean and intact:

• Angle Containers for Drainage: Place containers at an angle to help water drain easily, preventing pools of water from collecting in ridges.
• Secure Smaller Items: Use any clips or prongs to secure small or lightweight containers, which are prone to flipping over during the wash cycle.
• Avoid Overcrowding: Make sure there’s space around each container for water to circulate fully, which improves cleaning and reduces residue buildup.

As Olsen explains, plastic containers present unique challenges in the dishwasher: “Plasticware typically has two issues—it may have ridges where water can pool or accumulate, and ridges designed for lids to seal tightly. Plus, the surfaces of various plastic items are often rough enough to hold onto residual water.”

Pro Tip from Our Dishwasher Expert

While this may seem evident, always ensure that plastic containers (or any other items) are dishwasher safe before you put them in the dishwasher. Not all plastic is created equally, so look for the dishwasher-safe label before you potentially destroy your items (or your dishwasher)!