Much like its predecessor, the Platypus SoftBottle, the DuoLock is light, portable, and ideal for hiking in the backcountry or climbing up a multi-pitch route. The bottle is easy to fill, and the new lid makes staying hydrated a breeze. The downsides to this bottle are also similar to the SoftBottle. It is difficult to drink from at times since its flexible body is a bit floppy. Also, the bottle is one of the more difficult ones to clean due to its narrow mouth and some nooks and crannies that are hard to reach.
The DuoLock has a collapsible plastic body and screw-on cap. What sets the DuoLock apart from previous Platypus models is its newly designed two-part lid. The lid can be removed for filling, but it also has a flip cap that makes for easy drinking. We found that we spilled water on ourselves a lot less. Some bottles have similar lid designs, but the DuoLock's actually makes sense with the overall design of the bottle. Another plus for this contender is that it forms to the space available in your pack for easy stowing. The flexible body is also helpful when filling the bottle in shallow streams in the backcountry. It is leak-proof beyond any doubt, and easily rolls up and fits into your pocket when empty.
On the downside, drinking from this collapsible bottle requires a learned skill, and usually requires two hands. Its soft flexibility makes it flop around when trying to grab a drink, which will lead to spills if you're not careful. This is not a one-handed drinking bottle, but if you're using this bottle, hopefully, you are in the backcountry or on some kind of adventure where you will have time to use both hands to hydrate yourself. The DuoLock also had a tendency to fall over, which is a problem for all lightweight, collapsible bottles we have tested.
This contender also has one of the smallest mouths of all bottles we tested, making it hard to fill up from faucets with large or powerful water streams. Its narrow mouth also makes it quite challenging to clean. As we mentioned with the Platypus SoftBottle, the DuoLock has a small mouth that will require a different bottle for purification with some filters or a Steri-Pen. This is a reminder for those who are planning on taking this bottle into the backcountry. Liquid and tablet water treatments will work fine in this bottle, though, as would a Sawyer Mini water filter.
The DuoLock can easily handle drops and falls onto hard surfaces. It breezed through our drop tests, barely suffering a scratch (a minute scratch on the cap was all). That said, you can't expect a collapsible bottle to last forever. It held up fine in our three-month review, but in personal experience, we haven't had a collapsible bottle that held up much more than a year. For this reason, we recommend always having another water container as a backup. If you fold the bottle up for storage frequently, the bottle will wear more quickly along the fold lines and could risk having a hole form on the seam.
It is in this category that the bottle really shines.
The DuoLock is one of the lightest bottles in this review, weighing in at 1.6 ounces. That works out to being only five-hundredths of an ounce per fluid ounce. That means that the weight in your pack is not your bottle, but just the water you need to keep going on the trail. The other collapsible bottles scored right in line with the DuoLock in this metric.
Drinking from this water bottle tasted fine at first. However, if you store your water in this bottle for over 24 hours, expect it to have a plastic-y taste. It also retained the taste of the flavored sports drink in subsequent fills. Much like the LifeStraw Go, we recommend filling the PlatyPus DuoLock with water only. This is the downside of the bottle being plastic, and collapsible as the flexible plastic seems to impart its flavor on the liquid more than solid plastic bottles.
Unfortunately, the DuoLock had some issues with soapy flavor retention. After an issue with lingering soapy flavor, we were able to return the bottle to a neutral taste after filling it with baking soda and vinegar for 12 hours and rinsing. The best way to use these malleable plastic bottles is to simply use them for drinking water and try not to get other flavors imparted into their plastic walls.
The Platypus DuoLock is an ideal bottle for backpacking and traveling — not so much as an everyday urban bottle. Its lightweight design, clever lid, and incorporated carabiner clip make this bottle a great option for those counting ounces for their next adventure. The flexible body can collapse into the size of a plastic bag and stows away easily. It is easy to fill this bottle from a stream, but the narrow mouth makes it hard to filter water. It also requires two hands for drinking, which means it is not the ideal bottle for road trips. Overall, the DuoLock is a great bottle and our Top Pick for collapsible bottles.
If you want a non-plastic collapsible bottle, the Hydrapak Stow is a lightweight silicone option that folds up small and is ideal for uses like stashing into your jacket for sips of water on the ski hill. Our long-standing favorite all-purpose backcountry bottle is the Nalgene Wide-Mouth. If you just need an around-town daily driver, check out the Yeti Rambler 26, which is our favorite overall due to its ease of use and durability.
