Your Travel Mugs Are Probably Full Of Mold

May 07, 2023

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It's time to throw it away.

We love going to Starbucks for their drinks and pastries, but we're also obsessed with their merch. There's always a new lineup of cups and tumblers in various glittery and brightly colored hues.

You can also get 10 cents off every order when you bring a reusable cup, and members get 25 stars added to their rewards account. It truly pays to be sustainable.

But one problem with reusable cups is keeping them clean. We admit that sometimes we’re guilty of giving our bottles and mugs a quick rinse between refills. Because at the end of the day it's just water, right?

Wrong! In fact, your travel tumblers are a breeding ground for mold—and not just along the rim. Depending on what type of reusable cup you have, you could have mold lurking within its walls.

TikTok user @chelseadahl posted a video after accidentally breaking her ceramic Starbucks cup. What she found inside was shocking, to say the least.

She revealed that the inside of her cup had a hairline crack, which allowed the contents of her morning coffee to leak inside the double wall.

Having two layers of ceramic material is a great way to insulate your brew and keep it from getting cold. However, you will always run the risk of mold development—with and without a hairline crack.

If you have one of these cups, flip it over and look at the bottom. Without fail, you'll find a small hole. But this isn't a mistake. In fact, it's a necessary feature for every double-walled ceramic cup.

According to Alix Tieben, owner of Mora Ceramics, these holes are created to allow hot air to escape when your cup is fired in the kiln. Without them, the mugs would explode before ever making it to the store.

But there's a catch: it also creates a path for water to collect within the walls. And, since mold thrives in moist and dark environments, this part of your cup is the prime location for it to proliferate undisturbed.

The only way to access the mold and remove it is to break the cup. So next time you’re browsing Starbucks’ new collection of travel mugs, you might want to skip over the ceramic options.

But don't worry: we’ve rounded up some other options that are just as adorable and aren't as susceptible to mold. These mugs all get their insulating power from double-walled stainless steel—so you don't have worry about hairline cracks or built-in holes contaminating your cup.

What reusable cup do you use? Let us know in the comments.

Gabby Romero is Delish's editorial assistant, where she writes stories about the latest TikTok trends, develops recipes, and answers any and all of your cooking-related questions. She loves eating spicy food, collecting cookbooks, and adding a mountain of Parmesan to any dish she can.

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