Guides · 3 min read
How to clean a thermos bottle
Daily rinsing, a weekly clean and the few things to avoid — so your bottle lasts for years.
Fjella · 1 October 2026
A steel insulated bottle is easy to keep clean. The most important things are doing it regularly — and letting it dry properly.
Every day: rinse and dry
Rinse the bottle and lid with warm water and a few drops of washing-up liquid. Use a bottle brush for the bottom. Let the bottle and lid dry separately with the lid off — trapped moisture is what causes bad smells.
Once a week: baking soda or vinegar
If the bottle has held coffee, tea or smoothies, flavours and stains can build up.
- Add a teaspoon of baking soda to the bottle and top up with warm water.
- Leave it for a few hours or overnight — with the lid off.
- Rinse thoroughly and let it dry.
You can also use equal parts white vinegar and warm water. Don’t mix baking soda and vinegar, and don’t screw the lid on while it soaks.
Don’t forget the lid
The lid is where most of the dirt hides. Clean the seal and the drinking opening with a small brush, and let the parts dry before you put them back together.
What to avoid
- The dishwasher. We recommend hand washing — it protects the finish, the engraving and the seals.
- Scouring pads and steel wool. They scratch the finish.
- Chlorine and bleach. They can damage the steel and the seals.
- The freezer. Water expands when it freezes.
The engraving can handle everyday life
The engraving on a Fjella is laser-made: the coating is removed so the text shows in the steel’s own colour. It won’t wash off — but hand washing keeps both the finish and the engraving looking their best.
Read more about engraving, or see the bottles.
