And if you transfer the bottle to a bag, the bite valve folds down into the lid, shielding it from too much contact with the bag’s contents. What we’ve seen in years of testing is that almost every insulated bottle performs to within a few degrees of its competition.

So, “the copper liner needs to be: polished, installed in a vacuum, and done so in a manner that limits the amount of oxidation of the metal prior to pulling the vacuum. The HYBRID is the perfect bottle to have with you day or night, keeping your drink cold for up to 24 hours.Since we first created this guide, in 2014, we’ve tested more than 100 different bottles over many hundreds of hours. We believe good design is human-centered design, and that you should be able to absent-mindedly screw the top back on and trust that the bottle is properly closed. By reusing the bottles, you can do your part to reduce waste and play your part in a greener future.

We also set aside uncoated stainless steel bottles—if you leave an uncoated metal bottle in the sun, the exterior becomes too hot to hold. Why it’s great: The super-affordable 24-ounce Thermos Hydration Bottle has been a pick since we first published this guide, in 2014, and it’s still here.

A former academic, teacher, and bicycle mechanic, he now finds joy in adventures as often as possible. The spout on this bottle is easy to drink from (and simpler to use than a sports cap), and the flip lid stays secure and out of your face. TOP INSULATION TECHNOLOGY: The Hydraflow Hybrid stainless steel water bottle features top of the line triple wall vacuum insulation with copper lining and a unique flip straw, ensuring maximum insulation for your warm or cold beverages.

But the sport caps that come on double-walled steel bottles are stiffer, so they’re easy to inadvertently leave open.If you’re seeking an especially sleek-looking bottle, the Purist Mover is a good choice, and its (non-breakable) glass interior prevents flavors from transferring. While we generally don’t love the feeling of threads on the outside lip, these don’t protrude much, and we quickly got used to the feeling.