Do You Need a Waterproof Backpack?

Do You Need a Waterproof Backpack

A waterproof backpack is a luxury that many backpackers lust for, but what does it really buy you? Most of the people that own waterproof backpacks still line the inside of their pack with a garbage bag or pack their gear in waterproof stuff sacks.

What is a waterproof backpack anyway?

When you or I use the word waterproof, we usually think it means “100% impervious” to penetration by water. But many companies take liberties when they say their packs are waterproof. More often than not, some parts are waterproof and some parts are not.

For instance, there are basically two parts to a backpack:

  1. The main “pack bag” that holds all the stuff you might want to keep dry, and
  2. The shoulder straps, hip belt, external pockets, and compression straps.

While it is possible to buy a backpack with a waterproof pack bag, it’s virtually impossible to get one where the external pockets, the shoulder straps, the hip belt, and the compression straps are impervious to water. Most mesh-covered shoulder straps and hip belts will absorb water in the rain and make you wet when you put them on.

So as a matter of definition, a waterproof backpack will have a waterproof pack bag and not leak, but its suspension and external pockets, straps, etc. are unlikely to be waterproof as well.

ULA Epic Dry Backpack
ULA Epic Dry Backpack

Dry Pack Bags

Backpacks and daypacks with 100% waterproof pack bags are usually classified as Dry Backpacks. They’re mainly designed for use by rafters, pack rafters, canoeists, urban cyclists, but they’re not the most comfortable things to backpack with for any distance because their shoulder straps and hip belts, if they even have them, aren’t up to snuff.

Here are a few examples:

One exception is the ULA Epic which is basically an external frame backpack used to carry a high-capacity rolltop dry bag. It is designed for long-distance backpacking because it has a good suspension system.

The Zpacks Arc Blast 55 Backpack is waterproof because its made with Dyneema Composite Fabric and seam-taped.
The Zpacks Arc Blast 55 Backpack is waterproof because it’s made with Dyneema Composite Fabric and seam-taped.

Backpacks with Waterproof Pack Bags

If you just want a regular internal frame or frameless backpack with a highly waterproof pack bag, here are the three things you should look for when choosing between the options available.

  • Waterproof materials including  Dyneema Composite Fabric (DCF), X-Pac, ECOPAK, and Liteskin, the higher the denier (fabric weight) the better for abrasion resistance.
  • Taped, not bound seams (although you can seam-seal bound seams to make them waterproof.)
  • Roll-top closures.

1. Waterproof Materials

The use of waterproof materials like DCF, X-Pac, ECOPAK, and Liteskin doesn’t make a backpack waterproof but it’s a start: the way the seams are constructed is an issue too, as we discuss below. DCF, X-Pac, ECOPAK, Liteskin have a waterproof film sandwiched between abrasion resistance fabrics like polyester which prevents water from soaking through.

Here are some of the popular, but small, backpack manufacturers that use these fabrics:

Pack bag fabrics like Robic, Dyneema Gridstop, and the High Tenacity Nylon used by larger, more mainstream, pack manufacturers aren’t waterproof.

2. Taped vs Bound Seams

Most DCF backpacks from Zpacks and Hyperlite Mountain Gear have taped seams, like tents, which prevent water from seeping through the needle holes used to join different pieces of material together or to attach the shoulder straps, hip belt, external pockets, and compression straps to the pack bag.

However, packs made with X-Pac, ECOPAK, and Liteskin by companies like Superior Wilderness Designs, Waymark, and Seek Outside have bound seams (with visible needle holes), where the cut edges of the pack bag fabric are enclosed by another piece of fabric to keep them from fraying.

While bound seams are pretty tight, they can leak after use or submersion. You can seam seal them fairly easily, however, by turning a backpack inside out and brushing seam sealer over the needle holes. It’s a pain in the ass, but it’s a way for you to turn a water-resistant pack bag into a waterproof one.

3. Roll-top Closure

Roll-top closures are a must-have instead of top lids and extension collars because they prevent leaks if they’re made with a waterproof fabric and seam-sealed.

The only time I’ve felt the need for a waterproof backpack is for packrafting.
The only time I’ve felt the need for a waterproof backpack is for packrafting.

How is having a waterproof pack bag different?

How does owning a backpack with a waterproof pack bag change the way you use it? The answer is not much.

I’ve owned packs with pack bags made with every one of the waterproof fabrics listed above: DCF, X-Pac, ECOPAK, and Liteskin, and I still line all of them with a plastic bag and pack my moisture-sensitive gear inside waterproof stuff sacks the same way I do when I use backpacks that aren’t waterproof. The reason I like backpacks made with these materials is that they’re generally lighter weight and tougher than backpacks made with nylon and its variants. If I need more water protection for the bound seams, it comes from the plastic bag I use to line my pack.

The only time I’ve ever felt that I needed a truly waterproof pack bag is for packrafting. But even then a waterproof pack liner or drybag is usually enough to keep the contents of any backpack dry.

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5 comments

  1. A few thoughts:

    Compared to other PU-coated nylon backpacks I’ve owned, my Hyperlite Mountain Gear Windrider absorbs much less water in the rain, and doesn’t need a rain cover or pack liner for rain resistance. Less weight, and less weight. I still pack critical items in water resistant containers, but even on week-long rainfest trips, never got a drop inside the pack. Works great with an umbrella.

    And though I’m definitely in the minority, wearing a poncho over a backpack mostly makes the waterproof backpack argument moot, unless you are packrafting. Traditional ponchos don’t work well for trekking pole users, but something like the Packa or Decathlon’s ponchos-with-sleeves might work.

    “Waterproof” is in the eye of the beholder. Gear makers will always exaggerate. Backpackers need finer distinctions, like rainproof, short-submersion-proof, etc. Much like IP ratings for electronics – except those get exaggerated too.

    • I think the whole “backpack absorbs water and gets heavier” claim is a myth, which is why I don’t emphasize it as a benefit. Nylon just doesn’t absorb much water. Sure it gets wet which is gross and a hassle, but I’ve been hiking for years with nylon backpacks in the rain without a rain cover and never noticed they were substantially heavier. What’s a few extra ounces anyway. Just carry less drinking water.

      Completely agree that “Waterproof” is in the eye of the beholder. One of those terms, like “breathable” or “body-mapped” or “thermoregulation” that has essentially become meaningless, undefinable, hype.

  2. Nice article. It’s the when everything exposed to the elements is wet and heavy, including the pack (esp. with the hip belts, straps) that I dream of gear that repels water. Dashed my hopes, but saved me money. The weight gain with everything being wet is significant. One time I had a very small water absorbent towel. Towel seemed like a good idea until it was wet. The thing was heavy..

  3. Phillip,
    How do you close/secure the plastic bag after you put your items in? The only way I can visualize a completely waterproof scenario is if the bag was tied with a knot, which would be tiresome and bulky.

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