aiLabeling.aiLabelForImageAltText: Stainless steel thermos on a kitchen counter with cleaning brush and baking soda.

Cleaning Your Thermos: Tips and Tricks

Want to always have hot (or cold) drinks, but without any residue? If you want to enjoy your coffee, tea, and more on the go without a worry, you need to clean your thermos. It's neither complicated nor time-consuming—thanks to our tips, tricks, and kitchen hacks!

Thermoses and travel mugs should be rinsed after each use. For a deep clean, it depends on your favorite drinks:

For different drinks (e.g., coffee, then tea) –> clean weekly
For the same type of drink –> clean monthly

This is just a rule of thumb, so trust your eyes and nose: If you see buildup in the flask or mug, it's best to remove it right away. Also, be careful with insulated bottles that you only fill with water, as tap water can cause limescale buildup. You should remove this as well.

How to clean a thermos?

Thermoses come in different versions – stainless steel, coated, with a glass insert, etc. Different cleaning tips are suitable for each model.

Stainless steel insulated jug with a chrome handle and spout, on a white background.

How to clean a stainless steel thermos

The best way to clean your stainless steel thermos is with baking soda. Fill the thermos halfway with boiling water and add a packet of baking soda. Wait a few minutes until the baking soda stops foaming, then fill the rest of the thermos with hot water. Close the lid and let it soak overnight. Finally, rinse with clean water.

Safety tip: Only close the lid when it has completely stopped foaming! Otherwise, the gases released during the reaction can build up.

Black thermos with a wooden handle on a kitchen table with cookies and tea.

Cleaning a coated thermos

For a coated thermos, use dishwasher tabs. Place one tab in the thermos and fill it to the brim with warm water. Close the lid and let the cleaning agent work overnight. Afterward, rinse thoroughly with clean water.

Person filling a copper water bottle from a tap in a kitchen sink.

Cleaning a thermos with a glass liner

Denture cleaner is great for cleaning thermoses with glass liners. Place one tablet in the thermos and fill it with warm water. Let the cleaner sit for about 10 minutes, then rinse the thermos thoroughly with clean water.

Bonus tip: Don't forget to clean the thermos lid. Simply soak it in lukewarm water with one of the recommended cleaners or dish soap. If possible, remove any sealing rings and clean them separately. An old toothbrush helps with the grooves.

Cleaning your thermos with home remedies: What works and what doesn't?

Salt:
Fill the flask to the brim with hot water and add 2 tbsp of salt. Close the flask and shake vigorously. Let the thermos sit overnight.
Rice:
Fill the insulated flask halfway with warm water, then add a drop of dish soap and a handful of rice grains. Shake the flask with the lid closed—the rice will remove any buildup.
Potatoes:
Add a handful of potato pieces or peels to the pitcher, fill it with water, close the lid, and shake vigorously. After about 15 minutes, empty the pitcher and rinse it with clean water.
Lemon:
Fill the pitcher to the brim with boiling water, add the juice of half a lemon, and let it sit for 15 minutes. Then, drain and rinse.
Vinegar:
Add 1 tbsp of vinegar to the carafe, fill with warm water, and let the mixture soak for at least a few hours or overnight. Then, rinse with clean water.