Hydro Flask


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For thousands of years, mankind has carried water and sought better means to carry water. Over time, we’ve seen water-carrying technology go from sewn animal skins to metal canteens to plastic bottles to hydration packs – each with their positive and negative features. Indeed, the basic water bottle, a means of carrying enough water to slake thirst while between running water sources, has seen its share of design ideas and features: you can find a water bottle of virtually every size, shape, and color. Moreover, water bottles have sported a variety of means to get that water into your mouth: pour, squeeze, straw, flip top, and so on.

Sometimes, however, we outdoorsy people want a more durable means to carry water and occasionally carry something other than cold water or a sports drink – maybe hot water, coffee, tea, or soup. The thermal demands of hot and cold fluids coupled with a desire for minimal size and weight pushed water bottle manufacturers to again reconsider water bottle design. Combining new and old-school materials with unique design features, Hydro Flask offers a strong lineup of the latest in water bottle technology, including a 21 oz Standard Mouth Vacuum Insulated Stainless Steel Water Bottle. It keeps hot fluids hot, cold fluids cold, all in a very durable steel container.


  • Mouth Size: Standard
  • Mouth Width: 1.81 in
  • Bottle Weight: 10.4 oz.
  • Bottle Height: 8.87 in.
  • Bottle Height (w/cap): 10.56 in.
  • Bottle Circumference: 9.06 in.
  • Bottle Diameter: 2.85 in.
  • BPA-Free
  • 18/8 Stainless Steel
  • Lifetime Warranty
  • $25.99


I’m not sure what constitutes the perfect water bottle but the Hydro Flask I tested – color: Orange Zest – has to come close. An exercise in thoughtful design, the Hydro Flask endured all the rigors I could throw at it: it carried enough water for a daily hike or run, didn’t leak, kept my water at the temperature I like it, easily attached to a pack, and basically was the envy of everyone who saw it.

The Hydro Flask’s “Patented Standard Mouth Size” (1.81 inches) provided a good flow of water, even following a five-mile run, when thirst is high. Since it is double wall vacuum insulated, the water temperature was as cold as when I filled it at the water cooler, an hour earlier.

Made of 18/8 stainless steel (BPA-free) and coated in a powder finish, the Hydro Flask felt durable and robust. Although not attached to the bottle itself, the plastic cap featured a well-designed carry loop that would easily accept a carabiner.


Hydro Flask boasts that their water bottles “Keeps Hot 12 Hours and Keeps Cold 24 Hours.” I had no reason to doubt this but I ran a little science experiment to offer you something beyond me just saying that it worked.

To test the heat-keeping properties, I boiled 21 ounces of water in a tea kettle and put a cooking thermometer into the water. When the water cooled to 190 degrees Fahrenheit I poured it into a room-temperature (i.e., not pre-heated) Hydro Flask and put the lid on tight. It was 10:46 PM at this point so I went to bed. At 5:25 AM the next day I opened the Hydro Flask and inserted the cooking thermometer and got a reading of 142 degrees Fahrenheit.

To test the cold-keeping properties, I put 21 ounces of cold tap water in the Hydro Flask, right after emptying the hot water from the previous test. I measured the temperature of the water at 52 degrees Fahrenheit. Four hours later the temperature was 58 degrees Fahrenheit.

In other words, this Hydro Flask kept hot, hot and cold, cold – at least within a reasonable range for virtually any activity that would span a significant amount of time.


This water bottle sits in the middle of Hydro Flask’s lineup of water bottles in terms of capacity and size – sort of an all-purpose, all-around model. Its retail price of $25.99 is around the price you’d pay for a larger, heavier, but higher-capacity vacuum insulated steel beverage bottle – one meant more for a construction site than the trail. If, however, you’re interested the performance but not the physical size of such a bottle – as well as having a product that offers a lifetime guarantee – the Hydro Flask seems like an excellent value.


The Hydro Flask, in the very bright “Orange Zest” color, sells itself. My friends see it and want to know about it. When they feel its robust construction and hear about its thermal properties, they’re even more intrigued. The Hydro Flask’s appeal, then, is a combination of thoughtful design, excellent functionality, and fun.

Image by Mark Kakkuri

Any views or opinions expressed in this article are those of the author and do not reflect those of OutdoorHub. Comments on this article reflect the sole opinions of their writers.
  • Beau Petrone

    We are very happy with our 40oz Hydro Flaske bottles!!! Not only is it a great product but they offer wonderful customer service. I dropped 2 bottles head 1st onto concrete which cracked the lid(s) and would allow leakage to occur if the bottle was tilted or turned upside down. The Hydro Flaske company sent me 2 new lids without any questions or costs not even shipping! My only complaint is that it keeps my beverage too cold when I add too much ice! lol
    I will never buy another brand of water bottle again! Thank you Hydro Flaske!