Do You need a Pack Liner for a Waterproof Backpack?

Do You need a Pack Liner for a Waterproof Backpack

More and more ultralight backpacking packs are being made with waterproof materials like Dyneema Composite Fabrics (DCF), Ultra, Liteskin, EcoPak, and XPac. These fabrics absorb very little water and are bonded with a waterproof layer that prevents them from being soaked through when it rains and making your gear wet. Some are even seam-taped by manufacturers, so water can’t leak through the needle holes that are created in the pack fabric when the shoulder straps or hip belts are sewn onto a backpack.

Naturally, the question arises whether you still need a pack liner, like a plastic trash compactor bag, a nylofume plastic bag, or a high-volume DCF dry sack to protect your gear from getting wet if it rains.

Material Failure

While Dyneema Composite Fabrics (DCF), Ultra, Liteskin, EcoPak, and XPac are quite durable and abrasion-resistant, you can still wear a hole in them, especially on the bottom where they rest on the ground. A pack liner can keep your gear dry when the material starts to break down, leak, and then fail.

Seam-taping is also not foolproof. It can leak under pressure if you accidentally submerge a backpack or it falls out of your packraft and into the water. Seam tape also fails over time, with a lot of folding, scrunching, and rolling, especially in ultralight roll-pack backpacks.

Multiple Uses

But pack liners also have multiple uses beyond keeping the gear inside your backpack dry from rain.

For example:

  • Pack liners like the Exped Schnozzel can be used as inflation bags for blowing up air mattresses pads from Exped or Sea-to-Summit.
  • For keeping wet gear and clothing separate from dry gear and clothing inside your backpack.
  • To keep your gear dry from a leaky hydration system. Reservoirs, hoses, or gaskets leak eventually or you forget to close the top tightly and flood the inside your pack. I’ve had a 3L reservoir empty in a full backpack and the only thing that saved my bacon was the pack liner.
  • To store wet hiking shoes or a water filter inside your sleeping bag/quilt on very cold nights to prevent them from freezing while still keeping your sleep insulation dry.
  • Inside a sleeping bag as a vapor barrier liner for your lower body to stay warmer in freezing temperatures.
  • As a carry-on bag, when you’re forced to check your backpack for air travel.
  • As a makeshift poncho or vapor barrier booties, with the help of a pair of scissors.
  • There are even more creative ways to cut them up and use them in an emergency.

No Substitute

If you consider the attributes that make a waterproof pack liner valuable and unique, the one thing that stands out is its volume. It’s big enough to hold anything in your other stuff sacks with room left over. It’s often large enough to provide shelter or rudimentary clothing for a person in an emergency. There’s really nothing that comes close to its degree of utility in your backpack and there’s no way to backfill for it with any of your other stuff sacks or gear.

Discuss.

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11 comments

  1. Just finished a hike of The West Highland Way in Scotland as a daughter-father adventure to celebrate her high school graduation. As has been my practice for a few years, I used an Exped Schnozzel as my bottom-of-pack dry bag for sleep system and clothing. Fortunately I had my quilt and clothing in additional waterproof sacks, because the Schnozzel wet through during two days of near constant rain. This was not condensation from already-wet gear. I doubt I’d use the Schnozzel again when I know there’ll be wet conditions. I’d probably use only compactor bags in that case and use the inflation sack that came with my Nemo sleeping pad.

    • The seam tape came off my first Schnozzel after a few years. Exped replaced it for free after I contacted them and sent some photos. Contact them.

      My new Schnozzel is also my pillow. I put my down puffy in there with any extra clothing and it serves that purpose very well.

      • I’ll have to give mine a test when we get home. It seemed airtight while inflating my pad, but of course I should check it thoroughly.

    • The rain has been awful in Scotland. End of May, my pack, and myself, got soaked on Rannoch Moor and Corrour. I find a pack liner a bit unwieldy so had the important stuff in dry bags. Normally that pack is watertight…
      I usually keep anything down or electronic double bagged anyway.

  2. Bill in Roswell GA

    My sleep system resides in the Schnozzel. Then everything into a Nylofume polycryo sack. Sleep gear deserves double protection! Polycryo is amazingly tough. Great list of inventive ways to use a packliner Philip!

    Pack raincovers are so 1990s…..and don’t do a thing for the pack portion against your back.

    FYI – Exped and Sea to Summit each have amazing customer service. I know hikers that had air bags from both that were replaced in a matter of days, and a sleeping pad or two. Also, Schnozzel and S2S inflator bags work with the Nemo Tensor.

  3. What’s your take on Hyperlite Mountain Gear pods when combined with a dyneema pack? Assuming the pod zipper is fully closed, and their are no pin holes, do you think they would provide sufficient water resistance? I recently acquired both, and so far all the trips I have been on have been relatively dry. I was thinking of doing a test run in the shower to see how water resistant this setup really is.

    • God no. The dry bags and pods that companies sell you are not very dry at all. Unless it’s made for white water rafting or canoeing (every wonder why those dry bags are heavier) it’s not waterproof. The fallacy about packing pods is that they compress smaller than a stuff sack. Nope. Water resistance. Maybe, since it’s a lesser standard. But you’ll have a hard time crawling into a packing pod when you get cold on a windy night.

    • I dropped my HL Junction in a creek while crossing. I was using pods. My clothes and quilt got wet. The pods also resulted in more unused space. I quickly went back to a compactor bag and no pods.

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