You're Ruining Your Stanley Cup by Cleaning It in the Dishwasher. Here's a Safer Way

If you bought a Stanley tumbler during its viral rise to fame, it's time to give it a deep clean. Even if you only use it for water, that reusable mug with all its nooks, crannies and rings is almost certainly harboring mold or some other substance you don't want near your water -- let alone your mouth. 

The very components that make the Stanley so convenient -- straw, lid and various crevices -- also create multiple surfaces where bacteria and residue can accumulate. While tossing the tumbler in the dishwasher might seem logical, cleaning professionals advise against this method. Proper maintenance is essential to prevent the buildup of grime and potential mold growth, but the dishwasher may not be the most effective solution for these complex designs.

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We turned to an expert for the best way to clean a Stanley travel mug. 

"Cleaning Stanley cups regularly is essential to keeping them clean and safe to drink from," says Sabrina Tretyakova of Fotador, a cleaning technician certified through the International Sanitary Supply Association. Factors that influence the growth of bacteria and mold on Stanley cups include moisture, nutrients from the beverages themselves, and lack of regular cleaning," she says.

Parts of your Stanley mug that need cleaning

There's more than meets the eye when it comes to the various parts of your Stanley cup or insulated mug, and it's not enough even if you're regularly washing the inside of the cup and the sipping mechanism. Here are several problematic areas that Tretyakova identified:

Under the spout protector

Depending on your drinking vessel, this is easy to miss as it's not a piece that your mouth directly touches. However, it frequently comes in contact with the spout that your mouth touches, allowing bacteria and mold to accumulate.

Straw and lid

"These parts are prime locations for bacterial growth because they come into direct contact with your mouth and the beverages," says Tretyakova. "The bacteria can be oral flora, which lurks in your mouth and gets transferred to the cup." (If the words "oral flora" didn't send you directly to the kitchen sink for immediate deep cleaning, I don't know what will.)

Rubber seals

Specific models have rubber seals on the lids to help keep them closed tightly, but this is another area that Tretyakova identified as being troublesome regarding hygiene. "The areas under the seals are vulnerable to mold contamination if not cleaned properly," she says. "Usually, this area gets infested with black mold, also known as Stachybotrys chartarum." (Choose your adventure: Which is scarier, oral flora or black mold?)

How to clean your Stanley tumbler or insulated mug

Here are Tretyakova's recommended best practices for cleaning and maintaining your insulated mug.

1. Regular rinsing

"Rinse the mug and the lid under hot water shortly after drinking the beverage," says Tretyakova. "It helps remove any residue that could potentially harbor bacteria." This isn't in place of cleaning the mug, but it is a good habit to get into, especially if you're in a work or public environment and aren't immediately able to attend to it.

2. Thorough cleaning

First, disassemble your Stanley mug or other insulated mug completely so that there are no hidden areas that may harbor moisture and can encourage bacterial growth. Tretyakova recommends mild dish soap and warm water to soak the cup's removable parts for 15 minutes. (Throwing the cup in there is also a good idea while you're at it.)

Scrub the parts with a clean toothbrush or bottle brush and rinse them with warm water. You can hand-dry any parts that are easily accessible with a clean towel, but other parts, such as straws, will have to air-dry.

3. Avoid the dishwasher

The Stanley mug and some other insulated mugs may be dishwasher safe, but using the dishwasher isn't necessarily recommended for the best cleaning. "The dishwasher may not reach all the nooks and crannies on the lid of your mug," says Tretyakova, who advises regular hand washing for the best outcome. 

4. Periodic deep cleaning

Tretyakova recommends periodic deep cleaning in addition to daily cleaning, which can be done with distilled white vinegar and baking soda.

Read more: Think Those Stainless-Steel Cookware Stains Are Permanent? Not With This Genius Hack

Steam clean for additional peace of mind 

For those about to swear off insulated mugs forever, take note: There is more you can do to keep your cup clean and sanitized. Similar to bottle cleaners sold as baby products, steam sanitizers are available for a multitude of home uses, of which insulated mugs are prime candidates.

"Rubber sealing rings and slide openings of lids can trap moisture, even after they have been washed, and straws are challenging due to their length and shape," says Nicole Backus, a product manager for Clorox Home Appliances. Where moisture is the problem, moisture in the form of steam can also be the solution.

"Sanitizing with steam is especially helpful, as steam can penetrate cracks and crevices where scrub brushes, soap and water cannot reach," Backus says. "Sanitizing even clean parts of your insulated mug keeps bacteria from growing on surfaces of the cup, inside and out, top to bottom." 

Sanitizing should be done after washing, not in place of, but for extra peace of mind, you can get a sanitizer for home use such as the Clorox 2-Tier Steam Sanitizer for as little as $50. (You already spent that on the Stanley so consider it insurance.)