Imagine you've been out hiking all day in the summer heat, sweat dripping off your brow with each step. Your throat is dry and parched, but you've got just the thing to lift your spirits. You set down your backpack, and reach inside, feeling the touch of steel against your fingertips as they grasp a stainless water bottle. Unscrewing the cap and bringing the rim to your lips, you prepare to be refreshed as you take a gulp of… steaming hot water.


Ordinary single-walled water bottles have almost no insulation, and will change temperature rapidly.

That doesn't sound very refreshing at all, now does it? When temperatures reach triple digits, a sip of cool water can put a smile on your face, but hot water will do just the opposite. Alternatively, when it's freezing cold outside and you're chilled to the bone, you certainly wouldn't ask for a nice cup of ice water. What you'll really want is a beverage that's the opposite temperature of your surrounding environment—that is to say, a cold drink when it's hot outside, and a hot drink when it's cold.

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However, this isn't an easy task. Left unobstructed, mother nature will inevitably alter the temperature of any beverages you have to match the ambient temperature. The scientific principle of thermodynamics tells us this transfer of heat energy must happen—it's only a matter of time.

Insulated Water Bottles

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Fortunately, humans have developed a way to fight this natural process: insulation. Insulation dramatically slows the transfer of heat , keeping hot things hot and cool things cool. When applied to water bottles, insulation can maintain the temperature inside for hours or even days, no matter its surroundings.

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There are many varieties of insulated water bottles on the market, so we decided to test three leading brands to compare the pros and cons of each. In addition to carrying and using each bottle on a daily basis, we performed a hot water test to see how well they actually insulate their contents in a refrigerator. For the purposes of this guide, we selected bottles that would fit a typical large cup of coffee (18 to 20 fluid ounces at most coffee shops). Here are the three bottles we tested:

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Read on to hear our thoughts on each bottle, and see how they fared in our testing.

AVEX 3Sixty Pour

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AVEX produces a wide range of beverage cups and bottles, both with and without insulation. This particular thermally-insulated model is called the AVEX 3Sixty Pour. Here are its key specifications:

  • Capacity: 24 fl oz.
  • Dimensions: 11.4″ tall, 3″ diameter
  • Dry Weight: 16.3 oz.
  • Construction: 18/8 Stainless Steel
  • Finish: Blue/Black (also available in Black/Green)
  • Special Features: 360-degree pour spout, insulated cup lid
  • Claimed Maximum Insulation: 16 hours hot, 30 hours cold
  • MSRP: $30

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The AVEX bottle is the largest of the three, both in internal capacity and external dimensions. It's nearly a foot tall, but provides some unique advantages as a result.

Unscrewing the top of the bottle reveals an insulated cup that can hold 6 ounces of your beverage of choice. Underneath the removable cup is AVEX's 360-degree pour spout, which provides a leak-proof seal. Twisting the pour spout one half-turn conveniently lets liquid flow from any direction the bottle is tipped.

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The pour spout can be removed and disassembles into two parts for cleaning. However, AVEX says you shouldn't leave the spout at home, since the bottle will not seal fully with the cup lid alone. If you're planning to primarily use the bottle to dispense drinks, this is not a problem, but it makes drinking directly from the 3Sixty Pour difficult. You'll need to remove the cup, set it aside, unscrew the pour spout, set it aside, and then drink from the bottle and re-assemble.

Fortunately, the pour spout can be swapped for an AVEX ReCharge AutoSeal flip-top lid, if you're so inclined. That lid is sold separately by AVEX for $6.

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Overall, we liked the AVEX bottle, and felt its vibrant blue color is quite appealing. The non-slip matte finish also helped us keep it firmly in hand. We'd probably end up buying the optional flip-top lid for daily use, since we prefer drinking straight from the bottle, but the spout-and-cup system is very good in its own right.


  • Kept liquid hot the longest of the 3 bottles we tested (see results chart below)
  • Convenient built-in cup and easy-to-use pour spout
  • Attractive vibrant matte blue finish


  • Cannot be used with only the cup lid, requires pour spout to seal fully
  • Difficult to drink directly from the bottle, unless an optional lid is purchased

Hydro Flask Wide Mouth Coffee

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Hydro Flask is a well-known name in the insulated bottle market, and its products can be found in many large outdoor goods stores. We tested a Wide Mouth Coffee bottle, which comes with a flip-top lid for quick sips of coffee or tea. Here are its key specifications:

  • Capacity: 20 fl oz.
  • Dimensions: 9″ tall, 2.9″ diameter
  • Dry Weight: 10.8 oz
  • Construction: 18/8 Stainless Steel
  • Finish: Mango (also available in brushed stainless or 5 other colors)
  • Special Features: Flip-top lid, sweat-free powdercoat finish
  • Claimed Maximum Insulation: 6 hours hot, 24 hours cold
  • MSRP: $28

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The Hydro Flask Wide Mouth Coffee is appropriately-named, since it's specifically designed for coffee drinkers. Its 20-ounce capacity is just right for a large cup of Joe, such as a Starbucks Venti. Also, its compact size and light weight make it a great choice for travel. It fits nicely into a car's cupholder, and isn't so tall that it gets in the way.

The Hydro-Flip lid design makes one-handed drinking a breeze—just apply a little pressure with your thumb, and it pops right open. No unscrewing a tight lid, and no separate parts to worry about losing or dropping.

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The only downside to this lid is that it seems to affect the bottle's insulation capabilities. With this lid installed, water in our Hydro Flask ended up about 30 degrees cooler than the other two competitors, after sitting in a fridge for 12 hours. We've noticed from previous experience that the screw-on Wide Flat Cap lids Hydro Flask offers for $9 are much better at retaining heat for long periods.

Hydro Flask offers tons of customization options to choose from—many capacities, mouth types, lid types, and color options. If you want a bottle in bright purple, or a tiny size for your kids to use, or even a huge 64-ounce insulated beer growler, they can accommodate.

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The Hydro Flask Wide Mouth Coffee is a good little insulated bottle for various uses. It may not retain heat for a full day in frigid conditions, but it does offer a lot of all-around convenience in a light and durable package.


  • Quickest bottle to drink from, with a simple flip-top lid design
  • Compact and lightweight
  • Lots of size, color, and lid options to choose from


  • Didn't retain heat as well as the other two bottles we tested, likely due to the flip-top lid

YETI Rambler

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YETI became successful with their famous line of “grizzly bear proof” coolers, and branched out into tough insulated cups and beverage containers. This model is a new addition to that line, called the Rambler. Here are its key specifications:

  • Capacity: 18 fl oz.
  • Dimensions: 9.5″ tall, 3″ diameter
  • Dry Weight: 15.9 oz
  • Construction: 18/8 Stainless Steel
  • Finish: Brushed
  • Special Features: “Over the Nose” ultra-wide mouth, TripleHaul 3-finger carry handle
  • Claimed Maximum Insulation: No claims made by YETI
  • MSRP: $40

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The YETI Rambler is a simple insulated bottle with a no-frills design. It may only come in one color, and it may only offer one lid option, but it's very good at what it does. Featuring a solid stainless design with a brushed exterior, this bottle is unquestionably tough. It also held its own in our insulation test, retaining over 60% of its heat after 12 hours in a refrigerator.

The Rambler's business end is topped off by an insulated TripleHaul cap, named accordingly due to the fact that it's designed to be carried with a three-finger grip. We also liked its “Over the Nose” wide mouth, which prevents you from bumping your nose or tilting your head back awkwardly with each sip. This design makes cleaning easy, too.

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One downside to the Rambler is its price, about $10 higher than the competitors here. At 18 ounces, it's also slightly too small to pour in some large-size coffees. This wouldn't be a big deal if YETI offered a slightly bigger size, but the next size up is twice as large (36 ounces).

As long as the lack of color choices, lid options, and size variety doesn't bother you, the YETI is a solid choice. It did a great job retaining heat, ending up only a few degrees cooler than the dual-capped AVEX, and if it's anything like YETI's coolers, it'll be serving us well for years to come.

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  • “Over the Nose” wide mouth makes it easy to drink from
  • Very good heat retention
  • Simple, no-frills style


  • No optional extras or color choices, and only three size choices
  • A bit more expensive than the other bottles

Insulation Comparison Test

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To compare the insulation abilities of these bottles, we poured equal amounts of boiling water into each, and then placed them inside a 40-degree refrigerator for 12 hours. After pouring from the kettle into the bottles, the water temperature started out at 205 degrees. We then checked the temperature of each bottle's water at several intervals: 1 hour, 2 hours, 6 hours, and 12 hours. Here are the results of our test:

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The water we started with is approximately the temperature of a freshly-brewed pot of coffee—just under boiling. A cup of hot coffee is generally considered ideal for drinking at temperatures in the 120 to 140 F range. So, all our bottles can keep coffee piping hot for at least 6 hours, even in sub-40F outdoor temperatures. This is impressive considering how fast the temperature of our control glass of water dropped—it was barely room temperature after an hour, and ice cold after less than two hours.

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By the 12-hour mark, the water in our Hydro Flask was still quite warm, but not what we'd consider hot. This actually exceeds Hydro Flask's claim that the bottle can keep beverages hot for 6 hours. We'd say it kept water hot for at least 8 hours. The AVEX and YETI were neck and neck until the very end, when the AVEX's contents remained 5 degrees hotter.

Overall, we'd say each of these bottles has its advantages. If you prefer drinking from a cup instead of a bottle, and want a little extra capacity to get through the day, the AVEX is a great choice. Anyone looking for a light and versatile bottle could be well suited by the Hydro Flask. And the YETI is simple and tough with very good insulation properties. Whether it's hot or cold outside, any of the three will help you pack a drink that's just the right temperature.

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