How Often Should I Wash My Reusable Coffee Mug?

If you’re one of the 83% of American adults who drink coffee, you’re probably faced with the age-old debate: how frequently do you need to clean your coffee mug?

On the one hand, you’re using your coffee mug for the same beverage every day. So why waste time cleaning it when you’re just going to use it again in a few hours? This is especially “true” if you have a travel mug that has a lid—because nothing is going in or coming out except coffee. Right?

On the other hand, your coffee mug is filled with hot liquid that can breed bacteria and gunk at the bottom of your cup. Plus, the old coffee can impact your new cup’s flavor. And don’t get us started on if you add milk or sugar to your coffee!

So which theory is right? How frequently do you need to wash your reusable coffee mug?

Wash your coffee mug daily.

While it might be easier to avoid washing your coffee cup daily, you could actually be doing damage to your health and your cup of brew if you don’t wash frequently enough.

First, coffee is a liquid. When liquid sits at the bottom of your mug, it actually breeds germs and bacteria at a significantly faster rate than a dry cup. Liquid also attracts insects and pests.

Second, coffee and tea are hot. This often leads to condensation on the inside of your cup, which creates a humid environment—especially if you have a travel mug with a lid that traps the moisture inside. Warm, damp environments fester gunk.

Third, milk and sugar are especially bacteria-prone. If you put any fix-ins in your coffee, these can actually sit at the bottom of your cup—even if it doesn’t look like there are any coffee drops left. Dairy particles can spoil, which can leave you with an upset stomach and “inexplicable” health problems. Sugar attracts microbes and insects that you could end up ingesting in your next cup.

Fourth, your coffee cup sees the world. You’re carrying it on the train with you. You bring it into your office when everyone has the flu. You put it down on the counter in the public bathroom. Your coffee cup is well traveled, which also means it’s accustomed to being bombarded with germs on the regular. If you want to protect your health from colds, the flu, and other infectious bacteria, you need to clean your coffee cup inside and out regularly.

A study at the University of Arizona actually found that 41% of tested office coffee cups were contaminated with coliform bacteria—aka fecal bacteria. A few sips of this bacteria won’t hurt, but over time this can introduce harmful toxins to your system that can lead to serious health problems.

And finally, coffee tastes better when it’s fresh. Leaving old coffee in your mug can worsen the flavor of your favorite coffees.

The definitive answer? Wash your coffee cup every day. This helps remove harmful microbes that could be sitting in the coffee that you drink daily.

You don’t need to wash your cup after every use, though. If you drink a cup in the morning and again in the afternoon, you can leave your coffee mug for your next cup. Then, wash your mug when you get home from work or school in the evening.

How to wash

Most people assume that a simple rinse is enough to keep away bacteria—but studies show that’s not enough. You need a soapy wash daily and a heavy-duty wash weekly to make sure all of that gunk is gone.

What do you need to do to thoroughly wash your coffee cup without taking up too much time or effort in your daily routine?

1. Wash with warm or hot water. Hot water helps kill bacteria. (Wear gloves so you don’t dry out your hands in the hot water.)
2. Use eco-friendly soap. Look for products that are plant-based and contain no parabens, sulfates, or paraffins (waxes). We especially recommend Castile soap, which is a versatile olive-oil based detergent. White vinegar is also a natural antibacterial that can quickly and effectively lift coffee stains.
3. Use a paper towel to wash. Sponges, especially office or communal sponges, can hold on to and breed germs. If you’re using a sponge, damp it and microwave it for 1 minute before use. This helps kill off any bacteria in the sponge. Don’t have a paper towel? Use your hands—they’re cleaner than the communal sponge!
4. Don’t forget to wash the lid and all crevices. Pay extra attention to the edge of the mug where you put your lips. This is where the majority of bacteria likes to hang out.
5. Dry using a fresh paper towel. Make sure you dry thoroughly to avoid leaving any moisture that could breed bacteria.

What if you’re cleaning a reusable travel mug? How do you get down in the bottom of the mug without getting your hand stuck?

Just let your hot water and soap sit at the bottom of the cup. Dilute 2 tablespoons of vinegar in one cup of warm water. The vinegar eats away at the bacteria while lifting stains. Let sit for 15 minutes. Then rinse, and you’re good to go. If you need to get in the hard-to-reach crevices, use a non-abrasive pipe cleaner or soft bristle brush.

Want to get rid of those coffee stains that seem to get stuck on your mug?

Create a baking soda paste. Mix 2 tablespoons of white vinegar in one cup of water. Then, add enough baking soda until it creates a slightly-wet paste (about 5 tablespoons of baking soda). Use a sponge or your hand (in gloves) to rub the paste on the stain.

Baking soda isn’t too abrasive, so it shouldn’t damage your favorite coffee mug, but it will help lift stains and odors to make your mug as good as new!

Use this baking soda and vinegar routine weekly to lengthen the life of your favorite mug.

Read: How To Clean And Care For Your Baking Ware

Washing tips

1. Use a stainless steel mug, especially for travel. Stainless steel is the most resistant material against bacteria growth. It’s also the easiest to clean and maintain for the long haul. Click to learn more about the benefits of stainless steel travel mugs.
2. Keep it reusable. Even if daily washings seem like a hassle, they’re still a better option than disposable cups. Plastic cups can leach BPA and other chemicals into your iced coffee, and paper products can change the flavor of your hot coffee. Plus, you’re throwing out at least one cup per day (if you’re an avid coffee drinker), which has major environmental impacts.  
3. Don’t forget to clean your coffee machine itself too! Learn how to clean your coffee maker in 3 steps here.
4. The cleanliness of your water will impact the brew of your coffee. Any toxins or minerals in your water can actually react with the coffee particles, making your coffee taste old or stale. If you’re continuously getting burnt flavored coffee without actually over-brewing, you may need to look at your water filter!

How often do you clean your reusable coffee mug? What are your coffee cleaning tips and tricks? Let us know in the comments below!