GoKawiilLifestraw Go: Despite being one of the most popular water-filtering products on the market, it did not meet my expectations for filtering. The double-stage filtration includes a hollow-fiber membrane and a carbon capsule, yet this is the only bottle that produces water with particles after passing through the Lifestraw filter. That's not to say the Lifestraw Go isn't safe to drink from. The particles were probably just sediment, but it did produce a relatively strong mineral taste compared to the other bottles on this list.
The Lifestraw Go is made of BPA-free plastic throughout and has three simple parts (bottle, cap and filter; four parts if you count the carbon capsule inside the filter). Overall, the Lifestraw Go feels pretty sturdy. I prefer the durability of stainless steel, but it's lightweight and comes with a carabiner, so it would make a good backpacking water bottle. Any time you use the bottle, let the water sit for a few moments to prime the hollow-fiber membrane filter.
Waterwell Ultrafiltration Travel Water Bottle: Waterwell says its double-stage filtration system removes 99.9% of waterborne pathogens, but based on the taste of the water that came from this bottle, I wouldn't be so sure. I didn't feel or see any particles like I did with the Lifestraw Go, but the taste alone was enough to make me wary of bringing this bottle into the backcountry for clean water.
The bottle and cap are made from BPA-free plastic and feel just as sturdy as a plastic bottle should. The filter is attached to the straw by a flimsy rubber tube, which could be the culprit behind the poor filtering. The water tasted sour, but I couldn't quite place the taste (sulfur, maybe). Despite its poor filter attachment and sour taste, the Waterwell is easy to use, with the same setup as most of the other bottles on the list: bottle, cap and filter. The water bottle filter detaches easily and the bottle opening is large enough to insert a standard dish scrubber.