How to clean a coffee thermos - Unifury

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How to clean a coffee thermos?


For those of us who enjoy a daily coffee, we're no strangers to the unsightly brown coffee stains that cling stubbornly to our beloved coffee thermos. The discolored marks irritate us despite our best efforts with soap and water.

That’s why the purpose of this article is to demonstrate how you can solve this problem. With these cleaning methods, you won't have to deal with stubborn stains, unpleasant odors. Let’s explore!

Salt And Ice Method

What You Need

To clean your coffee thermos using the salt and ice method, gather the following ingredients and tools: 

  • Crushed ice 
  • Sea salt
  • A bottle brush or cleaning cloth
  • Hot water

Sea salt and ice are 2 main ingredients in this method


  • Add crushed ice into your thermos, ensuring there is enough space left for the other ingredients. Then, sprinkle around 2 tablespoons of sea salt into the thermos. This step is important as salt possesses natural antibacterial properties.
  • Next, securely fasten the thermos lid and shake it well. It is similar to how you would shake a cocktail shaker. This action helps the salt and ice mixture scrub away any accumulated residue on the inner surface of the thermos.
  • After shaking, utilize a bottle brush or cleaning cloth soaked in hot water to thoroughly clean the inside of the thermos. If necessary, repeat the process until the thermos is completely clean.

Vinegar And Baking Soda Method

What You Need

  • About 118ml (1/2 cup) of white vinegar
  • 1 tablespoon (about 14ml) of baking soda
  • Hot water

Prepare vinegar and baking soda for this method


  • Pour the white vinegar and baking soda into the thermos. 
  • After that, you'll see the chemical reaction subside, which leads to frothing and fizzing. Add hot water until it is full. Do not put the lid back on now, as the vinegar and baking soda mixture may react strongly.
  • Leave the thermos with the vinegar and baking soda mixture to dissolve coffee stains for approximately 10 minutes. 
  • After the waiting period, take a bottle brush and thoroughly clean the inside of the thermos, ensuring to reach all areas. This step helps to remove any remaining residue or stains.
  • Finally, empty the thermos. Rinse it thoroughly using hot water to ensure no vinegar or baking soda residue is left behind. You may choose to wipe the thermos with a cleaning cloth or allow it to dry naturally.

Dishwasher Powder Method

What You Need

  • 1 tablespoon of dishwasher powder (preferably in powder form for its abrasive properties)
  • Hot water
  • Bottlebrush

Use diswasher powder to effectively clean your thermos


  • Add 1 tablespoon of dishwasher powder into your thermos. 
  • Next, pour some hot water over the dishwasher powder in the thermos. Close the thermos lid and give it a brief shake to distribute the powder evenly and initiate the cleaning process.
  • After shaking, fill the thermos up to the brim with hot water. Leave the thermos to soak without the lid on for a few hours, or you can even leave it overnight in the sink. This soaking period allows the dishwasher powder to work effectively in removing any stains or residue.
  • Once the soaking period is complete, pour about half the liquid from the thermos. Then, using a bottle brush, scrub the thermos' interior to remove any remaining stains or residue.
  • Empty the thermos and rinse it out multiple times to ensure that all the dishwasher powder and residue are completely washed away. After rinsing, it is best to let the thermos air-dry naturally.

Denture Tablets Method

What You Need

  • 1-2 denture tablets 
  • Warm or hot water


Using denture tablets is another ideal method


  • Pour lukewarm or hot water halfway into the thermos. Allow the thermos to soak for a while before adding the denture tablets. You should swish the thermos slightly to ensure the inside is thoroughly wet.
  • Add 1-2 denture tablets to the thermos, being cautious to place it inside a sink as the chemical reaction between the ingredients may result in fizzing.
  • Let the thermos rest for approximately half an hour without putting the lid back on. During this time, the denture tablets will work effectively in dissolving coffee deposits.
  • Once the thermos has soaked sufficiently, use a bottle brush to scrub the inside of the thermos, ensuring all residue is removed.
  • Empty the thermos and rinse it to remove any leftover denture cleaner. While drying, position your thermos right-side up and keep the lid off.

How A Thermos Works

A thermos operates by utilizing advanced vacuum-insulated technology to effectively maintain the temperature of the contents. Its innovative bottle-within-a-bottle design incorporates a vacuum layer between the inner and outer walls. This enables the maintenance of the desired temperature for an extended period.

A key advantage of this design is its nonconductive properties, minimizing heat transfer. Due to this, hot liquids stay hot, while cold liquids stay refreshingly cold. 

Additionally, the thermos's clever construction prevents condensation from forming on the outer surface. Thus ensuring a comfortable, room temperature, or cool touch regardless of the temperature inside.


Thermos function brings us convenience

Things You Should Not Do When Clean A Thermos

After discussing some helpful tips for cleaning your thermos, it is equally important to be aware of certain actions you should avoid during the cleaning process.

Firstly, avoid using chlorine or bleach for cleaning thermoses. These strong chemicals have the potential to be too harsh and may cause damage to the stainless-steel interior.

Additionally, do not use excessively hot or boiling water when cleaning your thermos is advisable. The high temperatures associated with boiling water can potentially harm the paint or exterior of the thermos. 

Furthermore, the extreme heat might lead to melting and could even disrupt the vacuum seal, compromising the thermos's insulation capabilities. So, it is essential to preserve the integrity of the thermos to ensure its optimal performance.

When Do You Need To Throw Out A Thermos?

Despite diligent care and regular cleaning, thermoses aren’t meant to last indefinitely. Recognizing when the time has come to replace your trusty thermos is essential. 

One clear indication is when it no longer effectively insulates the contents, whether hot or cold. When you notice a decline in its insulation capabilities, it is probably a sign that it's time to throw it out.

In addition to checking its insulation performance, inspect the thermos' interior for any chips or cracks. You can utilize your phone's flashlight to thoroughly examine. If you detect any damage, you strongly need to replace your thermos.

Faqs about cleaning coffee themos

What's The Best Way To Clean Tea Stains From Stainless Steel Thermoses?

When it comes to eliminating tea stains from a stainless steel thermos, a highly effective method involves using a mixture of vinegar and baking soda. This potent combination works wonders in combating any pesky liquid-based stains that may have accumulated inside your thermos.

Explore more: 

👍 Say Goodbye to Stains: How to Remove Tea Stains from Cups.

👍 How to Get Coffee Stains Out of Mugs: Effective Stain Removal Tips.

In Stainless Steel Thermos, How Do You Remove The Smell?

Removing any unpleasant odors from your thermos is very easy. Just use baking soda and mix it with water. 

In the next step, pour the mixture into the thermos. After the designated time, rinse the thermos thoroughly. Now, you can get rid of any lingering unpleasant smells.

👍 Explore more: Coffee Aroma No More: How to Get Coffee Smell Out of Cup.

Why Does My Coffee Taste Like Soap?

If you find that your coffee has an unexpected soapy taste, it could be due to inadequate rinsing of your thermos. Particularly if you have utilized the dishwasher powder method for cleaning. 

This strange flavor indicates that your coffee is not suitable for drinking. You need to promptly and thoroughly clean to ensure your thermos is free from any remnants of detergent or cleaning agents.


In conclusion, maintaining the freshness and quality of your coffee experience hinges on the regular and effective cleaning of your coffee thermos. This guide has provided comprehensive steps and tips for keeping your thermos in optimal condition. By adhering to these practices, not only do you extend the lifespan of your thermos, but you also ensure that every sip of coffee is as fresh and flavorful as it should be. Remember, a well-maintained coffee thermos is the key to enjoying your daily coffee ritual to the fullest.

You may aslo like: 

👍 Tumbler vs Travel Mug: Which One Should You Choose.

👍 How to Clean a Classic Coffee Pot: Tips for Sparkling Brews. 

👍 How to Clean Coffee Carafe: Easy Steps for a Spotless Brewer.

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