How to Waterproof a Backpack (2022)

Person in orange shirt and backpack walking through a river.
Table of Contents

    No matter what kind of outdoor adventurer you are, a waterproof backpack is an important requirement. Whether you’re flying down white water rapids, on a mountain expedition in the snow, of simply trekking through a rainy day, you need to keep your equipment dry. Every outdoorsman should know how to waterproof a backpack, at some point everyone will get caught in the rain. If your backpack doesn’t have good enough water resistance, your gear could end up soaked or even ruined. 

    Just like knowing how to attach a sleeping bag to your backpack, adding some weather resistance is basic backcountry knowledge. Some backpacks are available for purchase with a strong waterproof coating already applied, but these can be costly, more expensive than the alternatives. It’s also common for backpacks to be sold as “waterproof”, but in reality, they are only water-resistant. Anyone who’s been caught out by this before knows what a difference there is between these terms. Many backpacks come with rain covers to keep the worst of the moisture away, but this certainly isn’t a perfect seal, and most of the time your stuff will still get wet. A rain cover is ideal for trekking in light to moderate precipitation, but anything more will require more water protection. 

    Waterproofing doesn’t only apply to chemical sealants; it refers to any process by which you protect your gear from moisture. This includes the use of dry sacks and ziplock bags, which we’ll also explain. There are different ways to optimize protecting your gear, whether you’re hiking in drizzle or tackling white water rapids, we’ll explain your best course of action. 

    If you learn how to waterproof your backpack and other belongings, you’ll increase their life dramatically. Waterproofing is a part of the general care and maintenance of your gear, doing so properly means your equipment will serve you better, for longer. As well as preventing the destruction of your belongings if your bag gets soaked, it will improve the overall durability of your pack, and make you a better backpacker overall. 


    Man with a red waterproofed backpack on a trail in the forest.

    From simple rain covers to marine dry sacks, there’s a lot of options for waterproofing your backpack.


    Waterproof v.s. water-resistant

    In order to fully understand the level of protection you need for your backpack, You’ll need to understand these terms. There’s an important distinction between “water-resistant” and “waterproof” and it can mean the difference between a soaked backpack or safe and dry gear. 

    If a backpack, or any item, is labeled as waterproof, then it’s about submersion. This means your bag could fall into a river and go underneath the water, without letting any moisture inside. A level of protection this intense goes beyond rainstorms, it’s for extreme conditions and water-related activities. A truly waterproof backpack could follow you through a waterfall without letting any of your gear get wet. It’s important to notice that backpacks made from waterproof materials aren’t necessarily fully watertight. The fabric and zipper could be waterproof, yet the bag classed as “water-resistant”. 

    Water-resistance however, is an ambiguous term. The meaning is vague, so the level of protection you’ll get is also questionable. A water-resistant backpack might just about keep your gear dry in a drizzle, or it could be strong enough for a downpour. Look out for rain-coated zippers, a sign that the waterproofing is more serious. Very few backpacking situations require a fully watertight bag, and often water-resistant gear is protective enough. Of course, it depends on your backpack’s true capabilities, and the weather you expect on your trip.  


    Different ways to waterproof your backpack

    Like anything, there are a few different ways you could go about waterproofing your backpack. In theory, just putting your backpack in a large trash bags could count as waterproofing, however, we don’t recommend this as your best course of action. The level of waterproofing you require must be determined by your planned trip. If you’re expecting to cross a number of rivers or streams, or the weather forecast calls for heavy rain or snow, then you’ll need to put in some serious effort to prevent all your stuff from getting soaked. When you only expect sun or light rain on your trip, then your weatherproofing doesn’t need to be as intense. However, it’s always better to be prepared for the unexpected rather than suffer a nasty surprise. 


    Using a rain cover

    The most common form of waterproofing is to use waterproof material to cover your whole pack. This is usually in the form of a rain cover, which could either come built-in to your backpack or be purchased separately. This is a simple solution, but not the most effective. Even putting your entire backpack inside a waterproof bag or trash bag isn’t effective; if there’s a single gap in this material then water can enter and nothing inside your pack will be protected. You’ll need to judge whether this waterproofing is adequate for your trip. If light rain conditions are all that’s expected, then a rain cover is an ideal, lightweight solution. However, if you decide to go kayaking, for example, this option is completely inappropriate.

    If you were to participate in watersports without an adequately waterproofed backpack, it could actually be seriously dangerous. If you fell into the water, your backpack would be completely soaked upon submersion, making it incredibly heavy. Aside from ruining everything inside, this holds a threat of drowning. This is why waterproofing your backpack in an appropriate way is so important.


    Man standing in the forest in the rain.

    Rain covers are a simple and easy way to keep your gear dry when hiking in the rain.


    Using a pack liner

    A backpack or rucksack liner like the Osprey Ultralight Packliner is essentially a large plastic bag, which goes inside your backpack to hold all of your belongings. Usually, these bags are made from a thick and durable but lightweight waterproof plastic material. When you use a pack liner, you must always put the liner in your backpack first, then fill it with your belongings. Filling the liner bag first and then stuffing it inside your rucksack can cause tears, destroying its waterproof purpose. 

    Once your bag is packed, push the extra air out of the liner and twist to close. You can use a rubber band, or a bungee if there’s one built-in, to secure the closure. This isn’t a perfect waterproof seal, but it’s perfectly adequate for your purposes. Again, the main issue with this method is that a single puncture or failure leaves all your gear soaking wet. 


    Using individual waterproof bags

    Rather than relying on a single waterproof element to protect all of your backpacking gear, you can use dry dags to protect your belongings. By taking each piece of gear you have in your backpack, or at least the most important, and placing them inside waterproof bags, you can minimize the damage. Prioritize electronics and other items which would be destroyed if wet, as well as clothing and towels which would soak up a lot of water. This is the most reliable way of ensuring specific items don’t get ruined. 

    There is a range of products you can use for these purposes, ranging in effectiveness and price. The easy version is just Ziploc bags, which are made from waterproof materials but not very durable. Ziploc bags come in a huge range of sizes, they’re uber convenient for storing smaller items. It’s worth noting that while these bags will keep out moisture, they might not actually be waterproof. Grocery bags can be used in the same way, a more economical approach that can be just as effective if you’re careful.

    Heavy-duty high-capacity garbage bags can function as pack liners, but they aren’t nearly as durable as the real thing. It all comes down to the type of expedition you have planned; for light rain and wet weather, a ziplock bag is perfectly adequate to protect your phone from minor damage. Conversely, if you end up falling in a river, you’ll be buying a new cell phone. 

    On the other end of the scale, watertight stuff sacks called dry bags are designed to safely and efficiently pack your gear into waterproof bags. These are usually designed for watersports such as kayaking and canoeing, so they’re extremely waterproof. For example, Granite Gear Drysacks Stuff Sacks are ultralight sacks with roll closures to reduce the bulk of your gear, they’re extremely waterproof so perfect for protecting your gear while making it easier to pack as well! 

    The downsides to this method are that usually, it’s a bit over the top. Unless you’re fully submerged in water at any point on your trip, then this extreme waterproof packing technique is a waste of money and energy. However, if you’re setting off on a longer expedition where you may need to cross rivers or lakes, then this is definitely recommended.

    You should at least ensure your most important items such as your mobile phone and wallet are in a completely protective watertight bag. The sealing mechanisms included in dry sacks are always more reliable than a simple plastic bag or pack liner. Backpackers on long-distance hikes might appreciate the extra peace of mind, knowing the equipment they rely on is protected. 


    Red waterproof fabric.

    Any plastic bag or waterproof material can be used to help protect your backpack.


    Using a wax or spray sealant

    In the same way that you can waterproof a tent, you can use a spray or wax sealant to waterproof your backpack. Not many people use this method as it won’t fully waterproof your backpack, only add a degree of water resistance, or moisture-proofing. The level of weather resistance this method depends not only on the product you use but the material your backpack is made from too. This makes this method less reliable, but still worthy of consideration due to its practicality. Using a waterproofing agent is the most space and weight-efficient option, as it doesn’t require you to carry any extra gear. 

    A waterproofing spray is easy to use, just apply an even coat and allow it to dry. Waxing is a more involved and traditional way to add water-resistance to materials, and you could also seam-seal your backpack for maximum effectiveness. Unfortunately, there will always be weak points such as the zippers where water can enter, no matter how many sealing methods you apply. We recommend using a waterproof spray or sealant in conjunction with our other methods as a secondary measure. It’ll help keep moisture out of your backpack, but in a downpour, it’s not enough to keep your gear dry. 


    Using a dry sack

    If you want an entire backpack that’s truly watertight, you can put the whole thing inside a large dry sack. Huge waterproof bags like the Sealline Boundary 115-liter Dry Pack can hold your whole backpack and has straps for carrying itself. At this point, you may as well abandon the backpack altogether, but again this isn’t necessary unless you’re at risk of completely submerging your bag. 


    How to waterproof a backpack

    We recommend using a combination of all these methods in order to adequately waterproof your backpack. You’ll need to assess the expected weather conditions, and consider how many rivers and lakes you might cross. It’s always a good idea to protect your most valuable items in a watertight dry sack. Items also worth saving are paper maps and other items easily ruined. We advise that you pay special attention to the following items:


    • Mobile phones
    • Cameras and video recorders
    • GPS unit
    • Lamps and flashlights
    • Wallet including money and ID documents
    • Maps and guidebooks
    • Paper documents such as park passes 


    If your main waterproofing fails due to a tear or puncture, then at least these items will be safe. Some mobile phones are manufactured to be waterproof, the same goes for other items, but it’s better to be safe than sorry. If your rain cover, pack liner, or plastic bag lets water in, you’ll be glad of more reliable protection for your valuables. 

    Whenever you find yourself hiking in the rain, make use of your rain cover. Whether it’s built-in or separate, a rain cover is a super-easy, lightweight, and effective way to waterproof your pack from most bad weather. If you have the time, adding weather resistance to your backpack with wax or a spray is always worth the extra protection. 

    If you need more water protection, for example, while kayaking or if the weather forecast is particularly bad, then you’ll need to waterproof the majority of your gear. In this case, dry sacks make the most reliable choice, however, they can be a pricey choice. Plastic grocery bags, Ziploc bags, and garbage bags can all serve as less-expensive options. This is a great choice if you need medium-duty waterproofing on a budget. 


    An assortment of electronics.

    By waterproofing your backpack, you can make sure you protect your most valuable items.


    Extra tips for waterproofing your backpack

    There are endless tricks that every hiker develops over time to optimize their system, in time everyone develops their own. We’ll share a few additional tips to help you make sure your backpack stays watertight!


    1. Although soft items like your clothing and sleeping bag won’t be ruined by water, they sure will soak a lot up. If your backpack takes on water in any way, chances are, your clothes will soak it up. Although this has the benefit of perhaps saving more breakable items, it means your bag will become very heavy. Some items could take a very long time to dry in this circumstance, so put absorbent items in waterproof bags as well. 


    2. Towels fall under the category of absorbent items, but you can skip the long drying time at least. Use one of our best backpacking towels for a fast-drying and lightweight solution. 


    3. Remember that water can damage anything electronic. Don’t forget to protect your portable charger, cables, headphones, and any other tiny items. 


    4. If you’re using household plastic bags like grocery bags, keep an eye out for thicker material bags. Don’t be afraid to double bag it, and use twist turns for maximum waterproofing. 


    5. Keep your water bottle on the outside of your backpack. Obviously, you don’t want to introduce any water into your bag on purpose, so prevent spillages, and watch out for other liquid items like cosmetics too. 


    Final Verdict:

    There are many different methods you could use to waterproof a backpack, some highly effective, others are completely free. We recommend you combine a few different methods from our range of options, so you gain the setup that best suits your needs. A rain cover will shield your back from most bad weather, it’s super lightweight and easy to use. We recommend using a dry sack for your valuables in addition to this, for the extra protection in a rainstorm. A cheaper option would be plastic or ziplock bags, which can be just as effective. 

    A pack liner is a good choice in bad weather, and if you’re expecting particularly wet conditions combine it with extra dry sacks and grocery bags. If there’s a chance of full submersion at any point, make sure to keep anything absorbent in a waterproof bag. Clothing gets very heavy when wet, so avoid this added complication. Waterproofing your backpack is easy, it’s just about being prepared. Follow our tips and instructions and you’ll never be caught out in the rain again!


    Bonus tip: Check out this video for some tips on using a dry sack!



    Riley Draper

    Riley Draper is a writer and entrepreneur from Chattanooga, Tennessee. As a world traveler, he has been to more than fifty countries and hiked some of the most elusive trails in the world. He is the co-founder of WeCounsel Solutions and has published work in both national and global outlets, including the Times Free Press, Patch, and Healthcare Global. When he's not writing, he's probably on a hiking trip or climbing in the mountains.