Is Thermoflask dishwasher safe?
Sometimes — the stainless steel body is dishwasher safe, but the lid and gasket should be hand washed to prevent seal degradation and decal peeling.
Quick facts
| Dishwasher safe? | Sometimes — Sometimes — with care |
|---|---|
| Category | Drinkware |
| Source | AI-reviewed · manufacturer guidance & material science |
| Last checked | 2026-07-28 |
Why
The Thermoflask body is made of double-wall 18/8 stainless steel, which is non-reactive and can withstand dishwasher heat and alkaline detergent without rusting or warping. However, the lid contains plastic components and a silicone gasket that can degrade over time due to high heat and harsh detergents, leading to seal failure and loss of insulation. The manufacturer recommends hand washing the lid and gasket to preserve the vacuum seal and prevent decal peeling on the exterior. Repeated machine washing of the lid may cause the silicone to become brittle and the plastic to warp, compromising the airtight seal. The stainless steel body itself is durable and can be safely washed on the top rack, but the lid should always be hand washed for longevity.
How do you wash Thermoflask?
- Disassemble the lid by unscrewing the top cap and removing the silicone gasket.
- Hand wash the lid, gasket, and straw (if applicable) in warm soapy water using a soft sponge.
- Rinse all parts thoroughly to remove any soap residue.
- Wash the stainless steel body on the top rack of the dishwasher or by hand with a non-abrasive cleaner.
- Dry all components completely before reassembling to prevent mold growth.
- Reassemble the lid, ensuring the gasket is properly seated for a tight seal.
What happens if you put Thermoflask in the dishwasher?
If you put the entire Thermoflask in the dishwasher, the stainless steel body will likely survive many cycles without issue. However, the lid and gasket will suffer. After one wash, you may notice the decal starting to peel or the silicone gasket becoming slightly less pliable. After repeated washes, the gasket can harden and crack, leading to leaks and loss of vacuum insulation. The plastic lid may warp, making it difficult to screw on or seal properly. These failures are functional and permanent, requiring replacement of the lid assembly. The body remains intact but may develop minor water spots or mineral deposits that are cosmetic.
Frequently asked questions
- Can I put hot liquids in the Thermoflask?
- Yes, the stainless steel body is designed for hot liquids, but avoid filling it completely and let it cool before sealing to prevent pressure buildup.
- Is the Thermoflask microwave safe?
- No, the stainless steel body is not microwave safe as it can cause arcing and damage the microwave. The plastic lid is also not microwave safe.
- How often should I replace the gasket?
- Replace the silicone gasket every 6-12 months or sooner if it becomes cracked, hardened, or no longer seals properly.
- Can I put the Thermoflask in the freezer?
- Yes, the stainless steel body is freezer safe, but avoid freezing it completely full as liquid expansion may damage the seal. Leave some headspace.
More drinkware
Popular checks
Last updated 2026-07-28. General guidance — always check your product’s care label. How we verify · Dishwasher care guides.