How to Clean a Thermos The Right Way In 6 Simple Steps

A Thermos or insulated travel mug is a must-have item for anyone who heads outdoors with a hot drink (or simply drives to work on a winter morning). But thanks to morning coffee, soup, and other hot food, these containers can get pretty dirty and often take on odors. Want to know the best way to clean a thermos or travel mug? We’ll show you how.

How to clean a thermos the right way

How to Clean a Thermos or Insulated Travel Mug

Unlike metal water bottles, insulated travel mugs are often filled with drinks or food that can stain or leave an odor. Because of that, these reusable containers need a little extra attention.

Most of today’s Thermoses or insulated travel mugs are lined with stainless steel, but if yours is lined with plastic or another material, you can still follow these cleaning instructions:

1. Remove the lid and open (or take apart) any pieces you can. Place the lid and all its parts in a dish of hot, soapy water and let it soak for 5 to 10 minutes.

2. Meanwhile, use water to rinse out any remaining liquid or food residue in the Thermos or mug.

3. Pour 1 teaspoon of baking soda into the mug, then add about ½ cup white vinegar. Let the mixture bubble up and allow it to sit for 5 to 10 minutes. (For particularly stubborn odors or stains, let the mug and lid soak longer. You may also have to repeat this step more than once.)

4. Once the bubbles have settled, use a designated bottle brush to scrub the inside of the mug. Remove the lid from the soapy water and scrub that too.

5. Pour out the vinegar from the mug and wash both the mug and lid using hot, soapy water. Afterwards, rinse both several times with warm water.

6. Place the mug and lid in a drying rack to dry or if you’re able to reach inside, dry them using a lint-free dish towel. (Either way, it’s a good idea to leave the lid off the mug and allow it to air out.)

Note: Although insulated mugs and lids are sometimes dishwasher-safe, it’s best to wash lids by hand. Repeated trips through the dishwasher can break down the lid’s seal—not to mention, residue and mold can build up in the lid’s cracks and crevices.

Recommended Thermos Cleaning Supplies

Bottle Brush Set
Turbo Microfiber Bottle Brush Cleaner Pack - Set of 5 Long, Cleaning Brushes for Baby Bottles, Water Bottles, Straws, Tumblers, Wine Decanters and Flask - Kitchen Supplies
  • Assortment - The bottle cleaner brush kit includes 2 bottle brushes for water bottles and tumblers, a narrow brush for long neck or narrow bottles, a small baby bottle brush, and a straw cleaner.
  • Durable - Each dishwasher-safe baby and water bottle brush cleaner features a sturdy handle and neck, stiff Nylon bristles, and rust-resistant stainless steel.
  • Universal - If you need a water bottle cleaner to wash your favorite bottle, ours does the trick. It's compatible with Hydro Flask, Boon, Munchkin, Yeti, S'well, Ello, Contigo, and other bottles.
  • Versatile - This BPA-free bottle cleaning brush set is designed to give any water bottle, drinking glass, tumbler, wine decanter, set of kombucha bottles, and even the kitchen sink a good old scrub.
  • Customer Satisfaction - Contact us if you have questions or concerns about your pack of water and baby bottle cleaner brushes. Our team is on-call and happy to help.

If you have an assortment of bottles and containers to clean, this brush set will ensure that you have the right tool for the job. Each nylon bristle brush in this set is a different size or shape—there’s even a brush that can clean reusable straws!

Bottle Cleaning Tablets
BOTTLE BRIGHT unisex-adult Bottle Bright (12 Tablets) - All Natural, Biodegradable, Chlorine & Odor Free Water Bottle & Hydration Pack Cleaning Tablets Clear
  • All natural cleaning tablet: biodegradable, chlorine free, and environmentally safe. Absolutely no contest against other bleach based cleaners
  • Perfect for coffee tumblers & water bottles: removes stubborn stains and odors giving your tumbler or bottle a new and fresh look and smell
  • 0 scrubbing required: Great for cleaning stainless steel bottles and mugs, hydration reservoirs, coolers, dishes at camp, hard to clean plastic containers and bottles
  • Travel & camping ready: individually packaged with no extra equipment required means you can clean your containers basically anywhere
  • Made in the USA: proudly invented, manufactured & packaged in the good Ole U.S of a.

These bottle cleaning tablets from Bottle Bright are great for travel or camping or any other time you’ll need to clean a Thermos but won’t have access to your usual household cleaning supplies.

In the market for a new Thermos or other reusable container? Check out our post on the best insulated bottles, flasks, and containers.