Pack liners and rain covers for hiking: keeping your gear dry

Pack liners and rain covers are often treated as interchangeable solutions to the same problem. In practice, they protect against water in very different ways and fail in different conditions, and I think understanding those differences matters far more than just picking one over the other.

Here’s what pack liners and rain covers actually do, where each works well, where each falls short, and how I combine them as part of a broader waterproofing system.

Start with how water actually gets into a pack

Water gets into a hiking pack through more than just rainfall. Prolonged exposure lets the fabric wet out. Dense scrub and wind-driven rain force water through seams and zips. Creek crossings and slips can briefly submerge a pack, and water can also wick down shoulder straps and the back panel through capillary action, bypassing external protection entirely.

A useful waterproofing strategy accounts for all of these pathways rather than assuming rain only falls from above.

What a pack liner does well

A pack liner is a waterproof barrier that sits inside the pack and protects everything placed within it. When it’s rolled correctly and folded down, it isolates gear from water regardless of how wet the outside of the pack gets.

Pack liners excel in sustained rain, scrubby terrain, and situations where a pack may be briefly submerged. Because the liner moves with the contents rather than the pack itself, it stays effective even when water gets in through seams, harness contact points, or zips.

For me, a pack liner is the foundation of the whole waterproofing system, not an optional extra.

Pack liners and failure modes

Pack liners fail most often due to user error rather than material limitations.

If the top of the liner isn’t rolled tightly and tucked down, it can act as a funnel, letting water running down your back get in from above. Sharp items inside the pack can also puncture thin liners over time if they’re not managed carefully.

Durability matters more than weight here. A very light liner that fails early becomes dead weight, which is why I’ve moved to heavy-duty garden or contractor bags, since they tolerate abrasion and repeated use well.

I also prefer clear or white liners over black ones, because they let more light into the pack, making it easier to find gear at the bottom in poor light or at camp. As a general guide, bags around 50-micron thickness or greater offer a good balance between weight and puncture resistance.

Pack fit and how liners change load behaviour

A full pack liner can subtly change how a pack rides. By containing all the contents as one mass, it can reduce how well gear naturally settles into the frame if it’s packed carelessly.

A simple field technique helps here. I pack my gear inside the liner while the liner is already sitting inside the backpack, which lets it expand into the corners and contours of the pack, keeping load balance better and stopping the contents forming a rigid cylinder.

Drainage and hidden weight

When you’re using a pack liner, the pack fabric itself will often still get wet. In heavy rain, water can pool between the liner and the bottom of the pack.

Some packs include a small drain hole or grommet at the base to let this water escape. Others don’t, and if there’s no drainage, water can sit in the bottom of the pack like a bucket, adding significant weight without being obvious. It’s worth checking how your own pack handles drainage and staying aware of this during prolonged wet weather.

What rain covers do well

Rain covers protect the outside of a pack from direct rainfall. They slow down how quickly the pack fabric becomes saturated and help stop water pooling in external pockets.

In light to moderate rain, on open tracks, and for short trips, rain covers perform adequately. They’re quick to deploy and easy to remove when conditions change, and I think of them as exposure reduction tools rather than a waterproofing guarantee.

Where rain covers struggle

Rain covers are vulnerable in ways a lot of hikers only discover after a wet trip.

Wind can lift or shift them, dense scrub can tear or dislodge them, and prolonged rain eventually forces water underneath, especially around the harness and back panel. They also offer no protection during creek crossings or if a pack is laid down on wet ground.

In exposed coastal or alpine environments, a loose rain cover in strong wind can act like a small sail, and on narrow ridgelines or exposed spurs, that can affect your balance and stability, which is a safety consideration on top of simple waterproofing. Because rain covers protect the pack rather than the contents, any water that does get inside has a clear path to your gear.

Pack liner versus rain cover at a glance

This comparison is a good illustration of why the two tools aren’t substitutes for each other.

Why most hikers use both

Pack liners and rain covers operate at different layers of the system: a liner protects contents regardless of external conditions, while a cover reduces how much water the pack absorbs in the first place. Used together, they cut down both exposure and consequences, and I treat the liner as non-negotiable and the rain cover as optional, depending on terrain, forecast, and trip length.

Interaction with organisation and wet zones

Pack liners work best when combined with deliberate organisation.

Wet items such as rain jackets, tent flies, or groundsheets should stay outside the liner, so they don’t contaminate dry gear with moisture. I usually do this using external mesh pockets or by placing wet items at the very top of the pack above the sealed liner.

Rain covers don’t change this requirement. Wet items inside the liner still introduce moisture regardless of what’s happening outside the pack.

Creek crossings and immersion risk

River crossings are a common failure point for rain covers.

If a pack is briefly submerged, a rain cover provides almost no protection. A properly sealed pack liner, combined with targeted dry bags for critical items, is far more reliable in these situations. Before a crossing, I check the liner closure, minimise loose straps, and make sure essential items are independently protected in case the liner is compromised.

Managing a wet pack at camp

When it’s raining heavily, a real advantage of a pack liner shows up at camp.

A wet pack can be left outside the tent or in the vestibule to cut down internal moisture and condensation, while the sealed pack liner, holding all the dry gear, can be lifted out and taken inside the tent. That keeps sleeping gear and clothing dry and stops a soaked pack adding humidity to the shelter, and it’s especially effective during sustained rain or multi-day wet weather.

Weight, simplicity, and false efficiency

Rain covers are often chosen because they seem lighter or simpler. In reality, a saturated pack and cover can end up weighing more than a liner-protected system once everything is soaked. Pack liners add very little weight and simplify decision-making by protecting everything inside them, and they cut down the need to individually waterproof every item.

To me, simplicity comes from fewer failure points, not fewer components.

Common mistakes

Common mistakes include relying on a rain cover as the only waterproofing layer, failing to roll and tuck a pack liner correctly, placing wet gear inside the liner, and assuming pack fabric is waterproof when new. Another frequent issue is designing a system around ideal conditions rather than likely ones. I base my own waterproofing strategy on worst-case exposure, not an optimistic forecast.

Choosing a practical approach

For most hikers, a reliable setup looks like this: a durable pack liner as the primary waterproof barrier, dry bags for items that must stay dry even if the liner fails, and optional use of a rain cover when conditions are mild or exposure is low. This balances reliability, weight, and simplicity without turning waterproofing into a complex project.

Pack liners and rain covers solve different problems. One protects contents from all directions, the other reduces exposure from above, and understanding their roles, limitations, and interactions is what lets you combine them intelligently rather than relying on one and hoping for the best. The goal was never just keeping a pack dry on the outside. It’s keeping the gear inside functional when conditions turn poor.

Explore related guides

• How to keep your hiking gear dry and organised
• Stuff sacks and dry bags for hiking
• How to manage condensation in your hiking tent
• How to pack a hiking backpack
• River crossing techniques