ThermoFlask Water Bottle Review

Overall Score

Last Updated July 25, 2021
  • Ease of Use 70% 70%
  • Durability 80% 80%
  • Seal 80% 80%
  • Maintenance 60% 60%
  • Insulation 70% 70%

Key Takeaways


Multiple Tops Offer Flexibility

A straw top and a chug cap are provided


Easy to Carry at 24oz

You’ll have enough water for most medium-lenght activities without a bulky design


Hand-washing is Required

It’s not recommended to run this bottle through the dishwasher

“No Sweat” Bottle

Changeable Tops

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The ThermoFlask 24oz is an excellent choice for individuals that want a bottle capable of serving them across multiple activities. This is made possible by the two caps that are provided: a foldable straw cap and a screwable chug cap. This adaptable hydration companion, allows for casual sipping with the straw top and bigger sips during a workout with the chug cap. 

Beyond the functionality that comes with two caps, HydrationReview team found this bottle to be quite versatile in other respects as well. It was great for any physical or recreational activities as it held its temperature for extended periods, was easy to carry and withstood damage after minor drops. One negative aspect to point out is the need for hand-washing. None of the components are dishwasher safe and will require some TLC from the owner.

ThermoFlask on The High Line in New York City

The ThermoFlask was a great companion for a walk on the The High Line in NYC.

We’re fans of the ThermoFlask’s aesthetics. It’s tall, slender, and offers a selection of classic colors that can fit any style. We appreciate the minor details such as the rubber grip on the chug top that matches the body and the contrast of the logo with the bottle’s color. Overall, it creates a clean look that works in both casual or professional settings.

Ease of Use

The slender nature of the ThermoFlask makes it easy to be gripped and carried. If you prefer using the handles, you’ll have two solid options between the straw and chug caps. The straw cap has a horizontal finger loop, which is different from what you’d find on similar bottles. HydrationReview team members could fit either two or three fingers in the loop, but in any case they all found it more comfortable to use two. It’s a natural grip that makes carrying it easy whether you’re headed from your office to your car or going for a longer jog around the neighborhood. The straw on this cap is pretty easy to operate. There’s a plastic edge that can flip the straw open with a thumb or pointer finger. Once open, taking a sip requires medium suction effort and water flow is sufficient. 

ThermoFlask with weights and a workout mat.

The ThermoFlask providing pre-workout hydration.

The chug cap has a plastic loop that is roughly the same size as that on the straw top, but this one is meant for a vertical grip. The construction of this grip is objectively flimsier than the straw cap grip, however, during our testing period it got the job done even with the bottle at max capacity. Operating the chug cap was super simple and in a way, enjoyable, given the design. We liked how the cap could be spun with finesse during tightening and loosening without worrying about it falling off (the cap stays connected to the bottle top). Another notable quirk was the mechanism that keeps the cap locked and out of the user’s way during drinking. This is a great design detail that makes daily use easier and more enjoyable. 


This bottle is made of stainless steel which can, unfortunately, be prone to scratching and denting. During our testing we found the paint quality to be on-par with other bottles we reviewed and noticed minor scratches after rubbing against other items in our bags. Thankfully, the scratches weren’t very noticeable if viewing from more than a few inches away. 

The ThermoFlask took on a bit of damage after an accidental drop onto a concrete sidewalk. While no major damage was immediately noticed, upon closer inspection, there is a shallow, gradual, dent on the bottom where it made contact which causes a slight imbalance when the bottle is standing upright. The wobble is less noticeable when it’s full of water. None of the exterior paint chipped as a result of the drop.


Overall, the ThermoFlask is well sealed, especially if you find yourself mostly using the air-tight chug cap. However, we want to note the straw top will leak water if opened (even slightly) when positioned on its side or upside down. The water leaks from the air hole that is meant to keep the air pressure in balance during sipping. This means theoretically there’s potential for the entire contents to empty out due to user error. Users should be extra careful and make sure the straw is fully closed when stowing it in a bag or backpack. We recommend the fully sealable chug cap for these situations.


As mentioned in the product summary, this is the main downfall of the ThermoFlask. Per the manufacturer, it should be hand washed only. We recommend using a scrubber for the inside of the bottle, a smaller straw scrubber for the straw and then a dish brush or sponge for the straw and chug caps. There are small crevices on the cap that you’ll want to get into, especially if you’re using an electrolyte mixer. All in all it takes about 3 minutes to give it a daily clean. If you like everything you’ve read up to this point, you shouldn’t let this stop you from purchasing.

ThermoFlask against an urban art scene.

ThermoFlask is a great hydration tool for walks around town.

One reviewer offered a helpful perspective on cleaning the ThermoFlask:

“While a very adaptable bottle, I preferred only using it with water, primarily while at work or on short urban outings. Experiences with hand cleaning other hand-wash only brands exposed to electrolytes have made me shy away from using it with anything flavored and then attempting a deep clean. A persistent taste of stale electrolytes, if the cleaning falls short, can ruin a bottle for good.”


The ThermoFlask 24oz. performed well during temperature control testing. The water temperature only warmed up by 12.9°(F) after the full eight-hour period. This was more than satisfactory for the HydrationReview team, since in reality, we’re polishing off 24oz. of water in half or even a quarter of that time. With the addition of ice, you’ll be even closer to a constant 32°(F) for several hours with the option to refill and have the ice cool the next batch of water.

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