We have explored many iterations of the collapsible bottle over the years. We have found that it is surprisingly hard to make a new, yet still effective, bottle that is lightweight and compact. Yet it seems that Platypus has done just that with the Platypus DuoLock SoftBottle. This bottle is super lightweight, easy to carry, and has a revolutionary lid design that changed our opinion on collapsible bottles in general. The Duolock also has a carabiner attachment point that we found very useful for climbing, as it can be attached to your harness. There are many pros to this new design from Platypus, and we are happy to give the bottle the Top Pick for Collapsible Award this year. This bottle is best used for hydrating in backcountry settings — you can even fold it up and fit it in your back pocket, making it the most portable of the top-ranked water bottles tested. The carabiner clip-in point adds to its versatility in the wilderness.
Pro tip — On extended backcountry trips, we like coupling the DuoLock with a Nalgene.
Editor's Note: This product review was updated on March 25, 2022, to share more product recommendations for specific uses.
Useful carabiner attachment, well-designed lid, lightweight, very collapsible
Simple design, inexpensive, lightweight
Light, durable, resists flavors, simple design, wide mouth makes for easy filling
Affordable, insulates well, has interchangeable lids, easily portable
Lightweight, collapsible, simple design
Tips easily, hard to clean
Made of plastic, doesn't fit in all cupholders
Diameter too big for cup holders, wide mouth makes it difficult to drink from when walking or driving
Paint chipping after a few months of use, flip cap seemed to lack security
Not very durable, difficult to clean, retains flavors
This bottle combines a collapsible design with a spout for convenient, easy drinking
This bottle is recommended because it is simple, lightweight, durable and has a solid feature set
A tried and tested classic, this model is versatile and reasonably priced
This is one of our favorite bottles because it's easy to use, just the right size, lightweight and inexpensive
With its lightweight design and packability, this is one of the best collapsible bottles out there
Platypus DuoLock So...
CamelBak Eddy+ Trit...
Simple Modern Summit
Ease of Use(40%)
Platypus DuoLock So...
CamelBak Eddy+ Trit...
Simple Modern Summit
Nylon / polyetholyene
Eastman Tritan co-polyester
18/8 stainless steel
Bottle Weight per Fluid oz Capacity
Free of Materials
BPA, BPS, BPF free
BPA, BPS and Phthalate Free
Duo-Lock flip cap
Screw cap, flip top
Loop-top screw cap
Screw Cap, flip top
.75 L, 1L
14 oz, 25 oz, 32 oz
16 oz, 48 oz
14 oz, 18 oz, 22 oz, 32 oz, 40 oz, 64 oz, 84 oz
0.5 Ltr, Push-Pull cap
Show full specification detailsHide full specification details
Our Analysis and Test Results
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.
Ease of Use
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.
Should You Buy the Platypus DuoLock SoftBottle?
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.
What Other Water Bottles Should You Consider?
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.
The number of options out there for water bottles can be...
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