Bacteria May Be Lurking in Your Stanley Cup—Here’s How to Clean It
"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links."
[table-of-contents] stripped
People on social media are finding black spots in their water bottles.
Doctors say this may be mold or bacteria—but it’s unlikely to make you sick.
Here’s exactly how to clean your Stanley cup.
Stanley cups are having a moment right now, with everyone from soccer moms to Jennifer Garner using the insulated vessels. But several people are making discoveries about their beloved tumblers on TikTok: They can harbor and mold and bacteria. Luckily, learning how to clean your Stanley cup can go a long way in preventing the buildup of gunk.
At least that’s what one person on TikTok, Skylar Ray Rose, learned. She shared a “Stanley hack” video that went viral. In it, Rose talks about how she typically will remove the lid and straw to clean her tumbler. However, she noted that she recently learned she can remove the top section of her lid, too. “I literally have mold,” she said in the video, holding up her lid, which had previously hidden black spots on it. “This is so gross,” she added.
In a separate video, fellow TikToker Nicole Kramer shared the inside of her Stanley cup, which shows spots of…something. “I’ve been drinking out of that all weekend and all this morning during my workout. I’ve had the worst sore throat. I had no idea why,” she said. Kramer also wrote this in the caption: “I use my Stanley on a daily basis and it’s so easy to forget the last time you washed it when you never stop using it.”
To be fair, this situation isn’t unique to Stanley—there have been many stories and social media posts over the years about gunk build-up in reusable water bottles. But these posts and more are raising plenty of questions about whether this can make you sick, and how to properly clean your reusable bottle. Here’s the deal.
Meet the experts: Tanya M. Laidlaw, M.D., director of Translational Research in the Division of Allergy and Clinical Immunology at Brigham and Women’s Hospital and an associate professor of medicine at Harvard Medical School; Robert Laumbach, M.D., M.P.H., a researcher and associate professor of occupation medicine at Rutgers Environmental and Occupational Health Sciences Institute; Purvi Parikh, M.D., an allergist with Allergy & Asthma Network
How to clean a Stanley water bottle
Before we jump into what may or may not be lurking in your cup, The brand has very specific instructions online on how to clean a Stanley cup. The brand’s website says to clean tumblers in between each use with gentle dish soap and a dish rag, soft sponge, or small brush.
But Stanley also notes that most of its products are dishwasher safe (including its popular tumblers). Just separate the different parts of your tumbler (including various components on the lid) and put them in the dishwasher. Worth noting: The company says that hand-washing is the best bet to keep the finish or paint looking its best.
Keep in mind that you’ll want to give your tumbler a good scrub before tossing it in the dishwasher if you spot black gunk on it, Tanya M. Laidlaw, M.D., director of Translational Research in the Division of Allergy and Clinical Immunology at Brigham and Women’s Hospital and an associate professor of medicine at Harvard Medical School, says. “Simply putting it in the dishwasher doesn’t provide enough friction to truly rid the surface of the microbes,” she explains.
Overall, doctors just recommend cleaning your tumbler and any reusable bottles you use regularly within reason. “You don’t need to sterilize your cup,” Dr. Laumbach says. “Nothing is sterile unless you're in a hospital operating room.”
What are the black spots in my water bottle?
While plenty of people online refer to the black gunk as mold, it could be bacteria, says Robert Laumbach, M.D., M.P.H., a researcher and associate professor of occupation medicine at Rutgers Environmental and Occupational Health Sciences Institute. “It may be more likely to be bacteria than mold,” he says. “Both mold and bacteria can grow on moist surfaces, but mold prefers it a little drier and bacteria prefers it a little wetter.”
The bacteria can specifically be oral flora bacteria, Dr. Laumbach says, which is bacteria that’s already lurking in your mouth that simply got transferred into the cup. “It’s the bacteria from your mouth that’s growing in the drink or lid,” he says.
But that doesn’t mean it can’t be mold. “Both mold and bacteria can produce a black color,” says Dr. Laidlaw. “You can’t tell just by looking at it. Mold is absolutely an option, but so is bacteria.”
Can mold or bacteria growing in my water bottle make me sick?
Ick factor aside, Dr. Laumbach says this “organic material” is largely no big deal. “It’s relatively harmless,” he says. Dr. Laumbach also notes that, in most of the documented social media videos of the tumblers, the gunk is either under a portion of the lid or on the side of the inside of the cup. “It’s not necessarily proliferating in the drink,” he says.
If there is, in fact, mold growing in your lid or cup, it could make you sick, says Purvi Parikh, M.D., an allergist with Allergy & Asthma Network—it’s just not overly likely.
Dr. Parikh says you may have the following symptoms if you breathe in mold:
Coughing
Wheezing
Trouble breathing
And, if you happen to drink mold and are allergic to it, Dr. Parikh says you might experience these symptoms:
Headache
Rashes
Diarrhea
Vomiting
But Dr. Laidlaw stresses that this is harmless to most people, including to most of those with mold allergies. “It’s the breathing and inhaling of mold spores that tend to cause symptoms,” she says, noting that most people’s mouths and GI tracts are good at breaking down the proteins in mold. “If I had a mold allergy patient who said, ‘Oh my goodness, I had mold in my Stanley cup,’ I would just say, ‘Clean it,’” Dr. Laidlaw says.
Regardless of what that black stuff is, Dr. Laumbach says that the vast majority of bacteria and mold is “harmless” to most people who aren’t allergic to it and that it’s “highly unlikely” that anything growing in your Stanley tumbler will make you sick.
As for posts on social media attributing a sore throat to the mold or bacteria from their water bottles, Dr. Laumbach says it’s likely a coincidence. “It’s hard to imagine any circumstances in which bacteria like streptococcus that can cause sore throat would be growing in the cup,” he says. “Much more common is viruses, which would not grow in the cup.” Dr. Laidlaw agrees. “The concern I have is that people would rule out other things that are much more likely causing their symptoms and won’t go to the doctor to see if they have influenza or COVID because they think they got sick from mold in their cup,” she says.
Overall, Dr. Laumbach says the message is clear: “Just clean your cup.”
You Might Also Like
