2021 Best Insulated Water Bottles Keep Your Ice Cold Water Longest

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In the extremely hot summer days, if we want to drink with a reusable water bottle without lukewarm water throughout the whole long day, then the stainless steel insulated water bottle, with its vacuum insulation technology, is the best option for our ice cold hydration.

Vacuum insulation is not a new technology, it was invented by Sir James Dewar in 1892. The vacuum insulated bottle consists of two walls, which are placed on within the outer and joined at the neck. The gap between the two walls is partially evacuated of air, creating a near-vacuum which significantly reduces heat transfer by conduction or convection. Therefore, the temperature can be maintained within  the bottle.

We have known how vacuum insulated bottles keep ice water for a long period of time, but how can we buy or make a best insulated water bottle that keeps ice cold longest?


Copper Shield Lining Technology Make Better Insulation

Plus copper shield on the inner wall surface can significantly enhance cold retention performance to keep ice cold 15% longer, but only at the same time increase around 3% product unit cost from your stainless steel water bottle manufacturer in China.

The copper lining layer on insulated bottle can reflect heat radiation so as to keep heat energy stay longer period inside of the bottle to keep ice cold water longer time than a normal water bottle without copper-plated layer.

You can find information that some brands claim that they have tripled walls vacuum insulation. However, they are just paraphrasing and indicating that they have double walls insulation plus copper lining. Here’s production description of S’well bottle for your reference:

TRIPLE-LAYERED INSULATION: S’well Supernova 17oz stainless steel water bottles feature triple-layered, vacuum-insulated construction, and are designed to keep beverages cold for up to 36 hours or hot for up to 18 with our exclusive Therma-S’well Technology. Each water bottle features unique colors, prints, patterns and textures, all delivering superior functionality. And they are hand-wash only.


Double Wall Insulated Cap/Lid

Most of the stainless steel bottle caps are not double walls, and lack insulation design. But a double walls insulated lid does improve the whole insulation of water bottle to keep the beverages ice cold longer or hot longer.

The typical insulated cap design for stainless steel water bottle is the Flex cap of Hydro Flask water bottle, which helps hydro flask water bottle obtain great cold retention to keep ice cold water for up to 24 hours.


insulated water bottle cap keep your ice cold water longer


Smaller Mouth Less Heat Loss

There’s many video reviews on Youtube to compare which stainless steel water bottle works better in terms of heat retention. However, it would cause misunderstanding when the bottle tested by Bloggers are of different mouth sizes/different bottle sizes. Here’s an example to watch:

It’s obviously that YETI water bottle is a wide mouth water bottle while Hydro Flask & The coldest water bottle are standard mouth water bottles. Since there’s no lid on the bottle to test with ice cold water, YETI water bottle thereby works worst in the cold retention test.

It is Not a scientific question, and people can easily find out a water bottle with smaller mouth means less heat transfer to outside of the water bottle. There is no vacuum insulated layer in the mouth opening area to stop heat conduction, that’s why you won’t expect a tumbler can keep ice cold longer than a water bottle does.

Best Plastic Free insulated water bottle:Klean Kanteen vacuum insulated water bottle, TKPro


Steel Cap Make Worse Cold Retention

Klean Kanteen TK pro water bottle has great design and is 100% plastic free, but its insulation is not good, they only tell:

  • Climate Lock double-wall vacuum insulation keeps contents hot or cold for hours

You can not find any information about how many hours it can keep cold. But based on customer comments and ratting, we can conclude that its insulation is not as good as other stainless steel bottles.

The reason why steel cap makes worse cold retention than a plastic cap does is that steel material has much higher thermal conductivity than plastic material: The thermal conductivity of steel is measured at approximately 45 W/(mK), which is extremely low compared to copper and aluminum that exhibit a thermal conductivity value of 398 W/(mK) and 235 W/(mK) respectively, but it is still much higher than plastic material, which is 0.1~0.22 W/(mk).


The Bottle Cap & Gasket Design

  • Bottle cap threads on outer side have better cold retention.
  • The seal gasket is on lower part of the bottle cap and has better cold retention.
gasket at lower part on water bottle cap

These design details are easy to be ignored by a product designer, and there are many articles and videos to tell different stories and results about which one is the best vacuum insulated water bottle to keep ice cold longest.  You must be confused with so many results and comments and don’t know which insulated water bottle is worth to buy? Here’s our answer based on the bottle design and customer reviews on amazon:


S’well bottle keeps water coldest and longest  keeps water cold the longest  at 48 hours by feature Therma-S’well® Technology with triple-layered, vacuum-insulated construction.

  • The 9oz fits snugly inside hand-bags and lunch-bags. Keep beverages cold for 24 hours and hot for 12.
  • The 17oz emulates a standard size water bottle. Keep beverages cold for 36 and hot for 18.
  • The 25oz holds a workout amount of water, or an entire bottle of wine. Keep beverages cold for 48 hours and hot for 24.

Of course, a good manufacturer supplier can help to improve vacuum insulation of your water bottle during manufacturing & inspection processes. That’s why it is always important to work with a supplier whom is professional and responsible like “Ecoshine Drinkware Limited” who offer one stop solution for your custom insulated water bottle tumbler project from concept design, prototype sample, tooling development, trial run production, mass production, quality management, and final shipment to bring your product from “0” to market.

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