How to Clean a Stainless-Steel Thermos Bottle

Published August 6, 2018
Thermos and brushes

Is your stainless-steel thermos stained with coffee or tea? Did your child forget his thermos of soup in his locker for a week? Whatever the case, sometimes stainless thermos bottles need more than just a simple rinse. There are several methods you can use to clean this type of container safely and effectively.

Everyday Cleaning

General care for your thermos is important, but it's not like you can just stick your hand in it to clean the inside. Instead, it's best to follow a specific daily cleaning routine.


  • Bottle scrubber (look for these in the kitchenware or baby department)
  • Dishrag or microfiber cloth
  • Mild dish detergent
  • Towel


  1. Fill the thermos with warm water and a dab of dish detergent. Don't submerge your thermos in water; it's better to fill it.
  2. Allow it to soak for three to five minutes to remove any general crud.
  3. Wrap the dishrag or microfiber cloth around the bottle scrubber and use it to gently scrub the container. If there is stuck-on food in the thermos, use the bottle scrubber alone.
  4. Rinse with warm water.
  5. Wipe the inside with the towel and allow to air dry.

Remove Stains With a Baking Soda Solution

If your thermos is stained, water and dish detergent alone won't be sufficient. Baking soda mixed with vinegar or peroxide can be very handy for this type of cleaning.


  • ½ cup vinegar or peroxide
  • 2 tablespoons baking soda
  • Warm water
  • Towel


  1. Pour the vinegar or peroxide into the bottom of the thermos.
  2. Add the baking soda.
  3. Fill the remainder of the thermos with hot (the hotter the better) water.
  4. Let sit for several hours, like overnight. (Do not cap.)
  5. Dump the container and rinse thoroughly.
  6. Wipe out as much water as you can with the towel. Allow to air dry.

Dissolve Stains With Denture Tablets

Designed to remove stains, denture tablets can be a gentle alternative for cleaning your stainless thermos. You simply need two tablets and water. Here's how to do it:

  1. Drop the two tablets into the thermos.
  2. Place the thermos in the sink and fill it with water. This will fizz and overflow the thermos, which is why the container should be in the sink.
  3. Allow it to sit for several hours. Do this before you go to bed and it should be ready when you wake up.
  4. Dump the thermos and rinse thoroughly.
  5. Use the towel to wipe it as dry as you can, then allow to air dry.

Eliminate Grime With Baking Soda

Baking soda is a great general scrubbing agent to help to remove stuck-on grime, such as hardened food. It can also help with some stains. Try this a quick and easy method that doesn't require wait time.


  • Baking soda (one tablespoon for each two cups the thermos holds)
  • Bottle scrubber
  • Microfiber cloth
  • Water


  1. Fill the thermos with water.
  2. Add the recommended amount of baking soda per the size of the thermos.
  3. Use the bottle scrubber to agitate the baking soda in the thermos.
  4. Rinse and repeat as necessary.

Scrub Away Grime With Salt and Ice

You can also use salt and ice to scrub away stuck-on grime from a stainless-steel thermos. To do this:

  1. Fill the thermos ¼ to ½ full with ice. Don't use crushed ice or large cubes. If you have large cubes, consider using a plastic bag and a mallet or hammer to break them up a little.
  2. Add two tablespoons of salt to the thermos.
  3. Cap the thermos.
  4. Shake the thermos continuously.
  5. Check your progress every three to five minutes to see if the stain is gone. Replace the ice as necessary. (The ice will melt slowly, breaking apart and becoming slushy. This will make it ineffective.)
  6. Pour out the salty slush.
  7. Rinse and dry.

What Not to Do

It is important to use care with your stainless thermos or you could destroy the liner. This can result in cracks and cause corrosion over time.

  • Do not wash your thermos in the dishwasher, as the detergent and washing process will be too abrasive for it.
  • Use caution with harsh abrasives like Comet. These can scratch the thermos and crack the liner.
  • Bleach can also be hazardous for a thermos, so avoid using it.

Caring for Thermos Containers

A stainless-steel thermos is a great way to store hot and cold beverages or soups for lunch. However, cleaning them takes a bit of care. It's important to protect the liner of your thermos so it doesn't crack. Always use a gentle approach when cleaning stainless-steel items.

How to Clean a Stainless-Steel Thermos Bottle