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Platypus DuoLock Soft Bottle Review

The Platypus DuoLock Soft Bottle is a leak-proof soft bottle that you can roll up and use anywhere
The Platypus DuoLock Soft Bottle is a leak-proof soft bottle that you can roll up and use anywhere.

The Platypus DuoLock Soft Bottle is a soft bottle with a locking cap that’s designed to prevent leaks and lost caps. The DuoLock bottle also comes with a carabiner that you can hook around your finger, use as a pour handle, or attach to your backpack so it can’t pop out of a pocket accidentally. Like Platypus’ other soft bottles, the DuoLock bottles have a gusseted bottom so they stand up by themselves which is great when camping, they roll up small when empty and not needed, and impart no taste to your water.

I must admit, having a Platypus soft bottle cap that you can’t lose is really nice. I’ve been carrying a spare Platypus cap in my gear repair kit for the past five years. I once lost a cap on a very long backpacking trip and never wanted to experience that again!

Specs at a Glance

  • Size: 1 liter, 0.75 liter
  • Weight: 1 liter (1.6 oz), 0.75 liter (1.5 oz)
  • Material: Nylon and Polyethylene (BPA-, BPS-, and phthalate-free)
  • Dishwasher safe: top rack only

The DuoLock cap is connected to a pour spout by a plastic hinge, with a wire latch the snaps over the top of the cap to hold it closed securely so it can’t twist off or leak. You can also twist off the pour spout to give yourself a bigger opening, making it easier to clean or fill from natural water sources.

Left: Cap closed and locked; Right: cap opened
Left: cap closed and locked; Right: cap opened

The bottle is made with a very durable, puncture-resistant plastic that’s BPA-, BPS-, and phthalate-free. You can freeze them, which is nice in summer, and they’re dishwasher safe (top rack only.) Platypus soft bottles are also tough and durable. You can roll them up thousands of times, scrape them up against rocks, and drop them without worrying about tearing or bursting one.

Platypus DuoLock Soft Bottle

Easy to Clean
Water Filter Compatibility
Easy to Refill
Hydration System Compatibility

Not Recommended

While soft bottles are convenient for backpacking because they're so compressible, the Duolock bottles are not compatible with popular water filters. I'd give these a pass on that basis alone.

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For backpacking use, the new Duolock bottles are not compatible with the most popular hollow fiber water filters or purifiers like the Katadyn BeFree, the Sawyer Squeeze, or the Sawyer Mini, because the cap is not threaded and is a different size. If you need a soft bottle that is compatible with the Sawyer filters, I’d recommend using Evernew soft bottles instead. You also need to be cautious with the security wire that locks the Duolock Cap closed because it can break, although Platypus does sell replacement DuoLock caps.

However, for more casual use when camping, day hiking, the gym, and especially for air travel, Platypus DuoLock Bottles let you enjoy the benefits of an ultralight, ultra-compact, reusable, roll-up soft bottle on the trail or closer to home.

Disclosure: Platypus provided me with this product, but I wasn’t under any obligation to review it.

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  1. Lamenting the passing of the Platypus PlusBottle…

  2. Did they fix their garbage customer service?

  3. I had some of their original bottles from 15 years ago, and they seemed to be made of a dual layer plastic that would eventually delaminate along fold lines. Is this still the case?

    • I never had that happen to me. the only defect I’ve ever experienced with a Platy soft bottle occurred when the plastic around the base of the cap developed a crack, probably from material fatigue, but that was after 10 years of use. I thought I’d gotten more than my money’s worth though.

      • I’ve not had the delaminating problem either, but have had the plastic around the base of the cap crack and separate like you have, Philip. The only other problem I’ve had is losing them–dropping them at the airport, leaving them at my kids’ swim meets, the golf course, etc, because I use them all the time.

    • As with all Cascade products, my experience with Platypus has been extremely high quality products backed by a lifetime warranty, often with no questions asked. I have never experienced a failure of a Platypus bottle (Platy Bottles and Plus Bottles). I did have a problem with the hose on a Platypus hydration bladder in which the lining separated from the outer layer, but not only did Platypus immediately make it right, they replaced the entire hydration bladder with the (newly released at the time) Big Zip, which in my opinion was not only not necessary, but also a serious product upgrade for me.

  4. Nalgene canteen with a Jetflow hydration adapter lid. (63 mm female to regular water bottle thread male).

    Only issue is for Jetflow to keep them in stock.

  5. When you twist off the pour spout to make a larger opening, is the opening large enough to use a Steripen Adventurer?

    • Nope – I think it’s more of a frontcountry bottle for urban use. A bit disappointing for us old time backcountry users, but I’m sure it will do well with consumers. Certainly cheaper than the $40 aluminum bottles people tote around. Platypus still has a lot of other bottles that work for us though. If you want a clear bottle for a steripenm a wide mouth Nalgene is your best bet. Alternatively, a cut down platypus works well with a steripen and a lot of people use it. Just cut the top off son a diagonal, which is also useful for scooping water up in shallow streams. A plastic sandwich bag also works. :-)

  6. Are these compatible with the Platypus Gravityworks filter system?

    I assume if not directly, simply removing the cap and filling that way would still work.

  7. Am I missing something about how the cap closes?

    I’ve just got one of these now.

    The metal clip can be pushed off very easily, almost effortlessly, and then the top can lift up moderately easily.

    It’s far easier to imagine this accidentally opening in a backpack, compared to a bog-standard screw-top bottle.

    I feel like the very thing it claims to offer – a secure top to prevent accidental leaks – is exactly the thing that it does not provide, and is in fact its biggest failing.

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