How To Clean A Coffee Thermos? – 6 Easy & Effective Methods!

A coffee thermos has become a famous handy item to store any type of beverage. It maintains your takeaway drink at an ideal temperature and keeps its original taste all day long. However, one of the drawbacks besides its convenience and durability is the cleaning routine after use. 

Luckily, some tested cleaning tips allow you to retain your favorite container out of stains and unpleasant smells. Keep scrolling down to the end of our post to learn how to clean a coffee thermos properly!

How To Clean A Coffee Thermos?

A stainless-steel thermos is helpful for people who do not want to spend $1 per day to buy a drink at any convenience store. Though it is a bit harder to clean than a coffee mug, it’s not impossible. There are some safety items and a few successful methods you could use to get rid of stains and smells from your favorite container. Let’s explore more details in the sections below.

Daily Cleaning

The best way to keep your coffee thermos free of grimes is a regular cleaning routine, but it is not as easy as you might guess. To get it done, the five quicker steps below will help.


  1. Fill the container halfway up with warm water and a few drops of dish soap. Avoid submerging it in that liquid. It should be full of liquid instead.
  2. Let the container sit like that for five minutes to loosen any dirt.
  3. Take a bottle brush to scrub away any residue of it.
  4. Run the bottle through warm water several times. 
  5. Wipe it with a clean dishcloth and leave it dry naturally without the lid.

Salt And Ice Method

Using salt and ice might not be a familiar method you have heard of removing stuck-on grime for your coffee thermos. Surprisingly, it works best.


  • Ice cubes
  • 2-3 tablespoons of grain salt 


  1. Fill a quarter of your bottle’s volume with crushed ice cubes. It works best if you use bagged ice from your local stores. 
  2. Pour in 2 or 3 tablespoons of sea salt over the ice. 
  3. Seal the lid and shake it continuously. Remember to check your progress every two minutes to ensure all stains are gone.
  4. Empty the bottle and rinse it at a warm temperature a couple of times to scrub all leftover debris away. Then, allow it to air dry – with the lid off.

Vinegar And Baking Soda Method

If an everyday cleaning process still leaves stains at the bottom of your coffee thermos, it is the right time to get some stronger agents. A dash of white vinegar and baking soda should be a great choice in dealing with hardened grimes. 


  • ½ cup of white vinegar 
  • 1 tablespoon of baking soda 
  • Hot water and bottle scrubber


  1. Add the recommended amount of vinegar and baking soda to your thermos. Shake the mixture regularly until you see a chemical reaction occur. Remember to place it above the sink just in case the foaming is over.
  2. Wait for the fizzing situation to calm down, and then fill up the flask with hot water.
  3. Leave it to sit for 15 minutes without putting the lid back on. Next, remove any buildup stain inside of the bottle with a brush.
  4. Give it an empty and rinse it with hot water twice to ensure no vinegar or baking soda smell still remains. You can wipe out as much as you can with the towel, but it is better to let it air dry naturally. 

Dishwasher Powder Method

Dishwasher powder is known as an effective cleaning agent compared to the liquid variant because of its abrasive feature. Therefore, it is used to scrape any type of stains, especially coffee grimes.


  • 1 tablespoon of dishwasher powder
  • Hot water
  • Bottlebrush


  1. Pour the dishwasher powder into your thermos and add some hot water over it, but keep in mind do not submerge them. Close the lid and shake it up briefly for 30 seconds. 
  2. Take off the lid and fill the thermos with hot water and let it soak for a few hours without the lid on. Place it in the sink and leave it overnight with the lid off.
  3. Pour half of the liquid out and clean the inside with a bottle brush in the morning. Next, blank it and give a good rinse a couple of times before letting it air dry.

Denture Tablets Method

Denture tablets are also an alternative item you could not ignore. Here is what you need and how to do it correctly.


  • 1-2 denture tablets
  • 6 cups of hot water
  • Bottlebrush


  1. Fill halfway up with boiling water into the thermos. Leave it to sit for 10 minutes to soften the stains and any residue.
  2. Drop 1 or 2 denture tablets inside it. It is better to hold your bottle over the sink because of the bubbles and foam solution.
  3. Wait for several hours with the lid off. Once it has soaked enough, scrub away any strains inside with a bottle brush and pour the mixture out.
  4. Clean it a few times with fresh water to eliminate all the denture cleaners. Wipe it out with a towel and let it dry without the lid.

Hydrogen Peroxide Method

If your coffee stains are too tough to remove, you might need a stronger cleaning substance called hydrogen peroxide. Peroxide can be used instead of vinegar due to its special characteristic – sanitizing the flask and cleaning it at the same time.

Although it works best on coffee stains, hydrogen is also useful for all items in your kitchen and bathroom. Nonetheless, if you use peroxide to soak this container, be sure to rinse it carefully after cleaning. To make it safer, it is advisable to give a quick clean with fresh water and dishwasher soap before using it.

How Do You Remove The Smell Of A Coffee Thermos?

The best way to get the smell out of a stainless steel container is by using a mixture of baking soda and water. The following ingredients and steps will help!

What you need:

  • 1 tablespoon of baking soda
  • Hot Water


  • Dump one tbsp of baking soda into the thermos
  • Pour lukewarm water over the baking soda
  • Seal the lid and shake the bottle for a few seconds
  • Before rising, leave it to sit for about 1 hour

If you are dealing with unpleasant smells, a mixture of baking soda, apple cider vinegar, and a cup of water is a more efficient method.

To get it done, add the above mixture into the container and let it stay there for a while. Remember to always rinse away with clean water before using it to get rid of any remains.

It is not recommended to use dishwashing soap and water to get out bad scents from your stainless steel coffee thermos for the sake of your safety. Go for natural agents such as soda and apple cider vinegar instead!

FAQs Of How To Clean A Coffee Thermos

1. How Do You Get Tea Stains Out Of Stainless Steel Thermos?

The best way to get rid of tea stains from a stainless steel flask is to use the baking soda method. Put three tablespoons of soda into it and fill it with warm water. Leave it to soak within 30 minutes, then rinse it clean. 

The mixture of vinegar and baking soda will clean and remove any odor within that container.  

2. Why Does My Coffee Taste Like Soap?

Several sources create a soapy for your coffee taste. However, the main reason is that you had not rinsed your coffee flask properly when you used dishwasher soap for the cleaning routine! 

To keep the original flavor for your beverage, be sure to rinse the thermos a couple of times after washing it with any chemicals and stronger cleaning agents.

3. Can I Use Bleach To Clean My Thermos?

Are you wondering if it is a good idea to use bleach to remove the stains and smells from your coffee containers? 

Do not use chlorine or bleach as cleaning agents because it will ruin and create other stains for your container. In other words, chlorine attacks and damages the protective layer of the stainless steel and then cause it to corrode. 

It is better to wash it in warm soapy water or a safer agent (hydrogen peroxide).


After reading our post, you now know how to clean a coffee thermos effectively, right? Although this item is a great way to keep the original flavor for your beverages, it also brings headaches when cleaning after use. 

We hope you can successfully apply the most effective tips listed above to get out unwanted coffee grimes. Thank you for your reading, and see you in our next article!

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