Is It Safe to Put My Insulated Cup in the Dishwasher?

There's nothing worse than opening your dishwasher and discovering that a favorite item, whether it's Tupperware or a tumbler, has been damaged during a 'convenient' wash.

When it comes to insulated cups, things get tricky. While their design makes them easy to carry and use, it may lead us to think they're dishwasher-friendly. But is that really the best option?

Given their surge in popularity as a must-have item, knowing whether or not your insulated cup can go in the dishwasher is more important than ever.

What Exactly Is an Insulated Cup?

To begin, it's important to understand the design of an insulated cup. Unlike regular cups or tumblers, an insulated cup features two layers: an inner and an outer wall, separated by a vacuum of air. This design helps maintain the temperature of your drinks—keeping cold beverages cool (even on sweltering days) and hot drinks warm (even when you're freezing on a chilly car seat).

Hand-Wash or Dishwasher Safe?

Chances are, your favorite insulated cup likely has a 'hand wash only' label rather than 'dishwasher safe.' This means the proper way to clean it is by hand, using warm soapy water and letting it air dry.

Handwashing is crucial for these cups, as the high heat of the dishwasher can damage the seals that maintain the vacuum. If the seal fails, it compromises the cup's ability to keep cold drinks cold or hot drinks hot. (We’re looking at you, travel coffee mugs.)

Additionally, the intense heat in the dishwasher can cause cracks in the cup's walls, allowing hot water to seep in between them. This trapped water can shift around, further damaging the cup and making its deterioration obvious with every step you take.

Depending on the material, the plastic of your cup could warp or become misshapen over time.

In an emergency, you could try placing the cup on the top rack and running it through a cycle without a drying phase (as this avoids the highest heat). However, this should be a rare exception if you want to preserve the integrity of your insulated cup. If the cup doesn't specifically say 'hand wash only,' it's safest to assume that only those labeled as 'dishwasher safe' should go in the machine.

More Tips for Cleaning Your Cup

Even with regular maintenance, stainless steel tumblers may develop discoloration or oxidation. To tackle these persistent marks, fill the cup with ½ cup of distilled vinegar, swirl it around, and let it sit for 10 minutes. Then, rinse thoroughly and scrub away any spots with a few teaspoons of baking soda using a non-metal bottle brush.

Let's be honest: you may have accidentally left yesterday’s coffee in your cup for an entire week. In this case, mix two tablespoons of baking soda with distilled vinegar, let it sit for 5 minutes, and voilà—your cup is sanitized and ready for another round, even after the most neglectful moments.

For an easy fix to eliminate odors, bacteria, or mold, try using water cleaning tablets. Just fill your cup with water, drop in a tablet, and let it sit for about 30 minutes. Afterward, rinse thoroughly with clean water to remove any cleaning residue.