Can Thermos Go In The Dishwasher?

By Cory White
Can Thermos Go In The Dishwasher?

Are you a proud owner of a trusty Thermos that keeps your beverages hot or cold for hours? As you enjoy the convenience and performance of your Thermos, you might wonder: Can you safely put it in the dishwasher? Not to disappoint, but not all thermoses are dishwasher safe, so checking the care instructions before cleaning is essential. Some thermos parts may be harmed in the dishwasher, while others may be suitable for dishwasher cleaning.

In this article, I will delve into the compatibility of Thermos with dishwashers, discussing the consequences of dishwashing a non-safe Thermos, warranties,  and Thermos parts and safety. Let’s go!

Identifying Dishwasher Safe Thermos

Identifying a dishwasher-safe thermos is essential to maintain its longevity and functionality. The process is simple and starts with checking any markings or symbols on your thermos.

  1. Most companies clearly mark their products with dishwasher-safe labels; these labels are normally found on the bottom or the side of the product.
  2. If you don’t see such a mark on your thermos, you can refer to the product manual or the company’s website. They provide detailed information about care and handling.
  3. A dishwasher-safe symbol, which typically looks like a box made of horizontal waves, can be a clear indication. This symbol has become widely recognized.
  4. Sometimes, if the thermos is dishwasher safe, it may have a label reading “top rack only.” This means that although it can go in the dishwasher, only put it on the top rack where the heat and intensity of the water stream are less.

Consequences of Dishwashing a Non-Safe Thermos

If a non-dishwasher-safe thermos is placed in the dishwasher, it can result in a variety of undesirable consequences. The dishwasher’s high temperature and strong detergents may accelerate the wear and tear of your thermos.

Loss of Insulation

Extreme conditions can affect the vacuum seal feature of the thermos, thereby reducing its ability to maintain temperature.

Loss of Aesthetic Appeal

The outer paint or finish may peel due to the hot water and harsh detergents, leaving your thermos looking worn and unattractive.

Loss of Integrity

The integrity of the thermos may be compromised. It might crack, warp, or even break apart due to the intense heat and powerful water jets.

Interior Lining Degradation

In some cases, the interior lining can degrade, which could potentially pose a health risk if it begins to mix with your drink.

Warranty Coverage and Dishwasher Damage

Understanding warranty coverage in relation to dishwasher damage is essential when using a thermos. Potential damages caused by cleaning methods could potentially void the warranty, depending upon the product’s policy.

Some thermos manufacturers might explicitly state that dishwasher-induced damages are not covered in their warranty policy. This often includes instances where the thermos wasn’t dishwasher safe but was still washed in one.

On the contrary, a few thermos companies may offer full coverage for dishwasher damages in their warranties, assuming that the product is designated as dishwasher safe.

Always read the warranty certificate or product details carefully to ensure you are aware of its terms and conditions. This can prevent unnecessary disappointments in the event of damage.

If the warranty is ambiguous or it’s unclear whether dishwasher damage is covered, it’s always a good idea to reach out to the manufacturer directly for more information.

Thermos Parts and Dishwasher Safety

When it comes to cleaning a thermos, it’s crucial to know that not all parts are created equal, especially in terms of dishwasher safety. Some parts may withstand the pressures of a dishwasher, while others may not fare so well.

Main Body or Canister

The main body or canister of a thermos is generally more resilient and, in many cases, dishwasher-safe. The high-quality material used in construction can usually withstand high water temperatures.

Lid or Cap

The lid or cap of the thermos is, unfortunately, far more susceptible. It often contains seals or other sensitive elements that the pressures and heat of a dishwasher can damage. So even if the body of your thermos says it’s dishwasher safe, the lid may not be.

Sometimes, a thermos may have a rubber or plastic seal inside the lid. If the seal is not removed and cleaned separately, it can retain odors, and flavors, or even get damaged in the dishwasher.

Other parts

Other parts, like a built-in straw or spout, may need special attention. They can get clogged with residues and might not be dishwasher-safe.

Alternative Methods for Cleaning a Thermos

vinegar and lemon

If your thermos isn’t dishwasher safe, don’t worry, there are several efficient and easy alternative methods for cleaning it.


The most basic method involves using warm soapy water. Fill the thermos with this solution, give it a good shake, and let it sit for a few minutes before rinsing.

Baking Soda and Vinegar

For a deeper clean, you can use baking soda and vinegar. Fill your thermos with a solution made from these, leave it for a while, and then clean with a non-abrasive brush.

Cleaning Tablets

Another practical method involves denture-cleaning tablets. Simply fill your thermos with warm water, drop in a tablet, and wait until it stops fizzing, then rinse thoroughly.

Bottle Brushing

One other frequently used method is the use of a bottle brush. These brushes are designed to clean hard-to-reach areas of the thermos that may often be missed.


In conclusion, when maintaining your thermos, it’s crucial to understand the varying dishwasher safety between different models and parts of the thermos. Inspecting your thermos carefully for dishwasher-safe labels and referring to the manufacturer’s instructions is the first step to proper care. Remember, only you can keep your thermos in top condition for longer, ensuring warm coffees in winter and cool beverages in summer. Your thermos deserves the care!

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