A waterproof pack liner helps keep essential gear dry when rain, wet vegetation and creek crossings expose your backpack to moisture.
Even a water-resistant backpack can let moisture reach its contents during prolonged wet weather. A damp sleeping bag or wet spare clothing can make camp uncomfortable, particularly when you’re several days from the trailhead with limited opportunities to dry your equipment.
A waterproof pack liner creates a protective barrier inside your backpack, helping keep vulnerable gear dry even when the outer pack fabric gets wet.
Choosing the right liner comes down to four practical factors: waterproof construction, closure design, durability and capacity.
Understanding how these features work together will help you choose a liner that fits your backpack, protects your gear and suits the conditions you expect to encounter.
What Should You Keep Dry Inside Your Pack?
Not everything in your backpack needs the same level of protection.
A backpack may resist light rain, especially if its fabric has a water-resistant coating. However, seams, zips and openings can allow moisture inside during prolonged wet conditions.
According to the Australian Bureau of Meteorology’s 2025 Annual Climate Statement, Australia’s nationally averaged rainfall reached 503 mm in 2025, 8% above the 1961–1990 average. Rainfall conditions varied considerably across the country, reinforcing the need for bushwalkers to prepare for the weather expected along their chosen route.
A waterproof backpack liner sits inside the main compartment, creating a separate waterproof barrier around the gear you need to protect.
This is particularly useful on multi-day bushwalks, school outdoor programs and expeditions, where wet equipment can create problems that are difficult to resolve away from shelter.
How a Waterproof Pack Liner Protects Your Gear
A pack liner works by creating a protected compartment inside your backpack.
Place the liner inside the main compartment before loading your equipment. Pack the items you want to keep dry, leave enough material at the top to operate the closure properly, then seal the liner before closing your backpack.
The backpack carries and supports the load while the liner provides the waterproof barrier.
Keeping the liner inside the pack also helps shield it from direct contact with branches, rocks and other rough surfaces that could damage the fabric.
What Should Go Inside Your Waterproof Liner?
Start with the equipment that would cause the most trouble if it became wet.
Your sleeping bag is usually a priority, followed by dry spare clothing and insulating layers. Depending on your trip, you may also need to protect electronics, maps or other moisture-sensitive equipment.
Items that are already wet, or can tolerate moisture, are often better stored outside the main liner or separated from dry equipment.
A useful question to ask while packing is:
What gear will I need to be dry when I reach camp?
Use the answer to decide what belongs inside your main waterproof liner.
What Makes a Pack Liner Waterproof?
Not every liner provides the same level of water protection.
The fabric, seams and closure all contribute to how effectively a liner keeps moisture away from your gear.
Waterproof fabric alone is not enough if water can enter through untreated seams or an incorrectly secured opening.
The Wilderness Equipment Pack Liners available from Offtrack use 70D nylon with seam-taped construction and a stated 10,000 mm hydrostatic-head waterproof specification.
These details provide a more useful basis for comparing liners than relying on the word “waterproof” alone.
Check the Fabric, Seams and Construction
Fabric choice affects both durability and weight.
A liner needs to withstand regular packing, unpacking and movement inside the backpack without adding unnecessary weight to your load.
Seam construction is another important consideration. Stitching can create potential entry points for water, which is why seam treatment matters.
For bushwalking and expedition use, look at the complete waterproofing system rather than judging the fabric specification in isolation.
Even a well-constructed liner needs careful handling. Sharp cookware, exposed tools and hard objects with pronounced edges can put unnecessary pressure on the material.
Pack these items sensibly to reduce the risk of abrasion or punctures during repeated use.
How to Close a Waterproof Pack Liner Properly
A waterproof liner needs a secure closure to protect its contents effectively.
If the opening cannot be closed correctly, water may enter regardless of the fabric’s waterproof rating.
The Wilderness Equipment pack liner stocked by Offtrack uses a non-wicking, drybag-style closure designed to help prevent moisture from entering through the top.
Why a Drybag-Style Closure Works for Bushwalking
A roll-style closure allows the opening to be secured without relying on a conventional zip.
For the closure to work as intended, you need enough spare material above the packed contents.
Avoid filling the liner completely to the top. Bring the opening together, remove unnecessary trapped air and secure the closure according to the product instructions.
The amount of space needed for this is an important part of choosing the right liner capacity.
Why Overpacking Can Reduce Waterproof Protection
A liner may hold all your gear but still be too small for practical use if the contents prevent the top from closing correctly.
Bulky sleeping bags, insulating clothing and irregularly shaped equipment can also take up more room than expected.
This is why the usable capacity of a liner matters more than simply fitting everything inside it.
Choose a size that accommodates your essential dry gear without placing unnecessary strain on the fabric or closure.
How to Choose the Right Waterproof Pack Liner Size
Your backpack’s capacity is the best starting point when choosing a liner.
However, the capacity printed on your backpack does not automatically tell you which liner will fit best.
You also need to consider the amount of equipment requiring waterproof protection, the bulk of your sleeping system and how the liner sits inside the main compartment.
Offtrack stocks red Wilderness Equipment pack liners in 60L, 80L, 100L and 120L capacities. Although their proportions are designed around Wilderness Equipment pack volumes, they can also be used with other backpack brands.
Compare the Available Pack Liner Sizes
The four available sizes provide options for different packing requirements.
| Pack liner size | What to consider before choosing |
| 60L | Check whether your essential dry gear fits comfortably, particularly if you carry a smaller or less bulky load. |
| 80L | Consider whether your sleeping equipment, spare clothing and other protected items need additional space. |
| 100L | Assess the amount of bulky equipment you need to protect on longer trips or expeditions. |
| 120L | Consider whether your larger load requires the additional capacity and whether the liner fits neatly inside your backpack. |
These are practical considerations rather than fixed recommendations for particular backpack sizes.
Two backpacks with the same stated capacity may have different internal dimensions. Your packing method and the amount of gear stored outside the liner can also influence the size you need.
Match the Capacity to Your Packing System
You do not necessarily need a liner that covers every litre of your backpack.
Some equipment can sit outside the protected compartment, while other trips may require most of the load to remain dry.
Think about your normal packing system.
A bulky sleeping bag and insulated clothing can take up considerable room, even when the total weight of the equipment is relatively low.
The Wilderness Equipment product specifications also list different open and closed heights for each liner, reflecting the material used to complete the closure.
If you’re deciding between two capacities, consider how comfortably your equipment fits and whether the larger liner creates unnecessary excess fabric inside the pack.
The best choice is the one that gives your dry gear enough room while allowing the closure to operate correctly.
Durability and Weight for Longer Trips
A liner used occasionally for an overnight walk may face different demands from one packed and unpacked every day on an extended expedition.
Repeated handling, shifting equipment and pressure from objects inside the backpack can gradually place wear on the material.
For longer trips, durability becomes an important part of the decision.
Why Extended Trips Put More Demands on Pack Liners
Each day of a multi-day trip involves loading, carrying and unpacking equipment.
A liner needs to remain practical through that repeated use.
For school camps and outdoor expedition groups, a consistent waterproofing system can also make packing easier to manage.
One main liner creates a clearly defined protected area inside each participant’s backpack. Smaller dry bags can then be used for equipment that requires separate storage.
The Wilderness Equipment pack liner is intended for extended travel through wet and remote country, with seam-taped construction and a drybag-style closure.
As with any waterproof equipment, careful packing and regular inspection remain important.
Consider the Weight Alongside Durability
Protection needs to make sense for the type of trip you’re undertaking.
The 60L Wilderness Equipment pack liner is listed at 144 grams.
If you’re comparing larger sizes, check their individual specifications rather than assuming they weigh the same.
For longer walks, consider the balance between the protection you need, the durability of the material and the total weight you’re prepared to carry.
Pack Liner vs Dry Bags: Which Should You Use?
Pack liners and dry bags both help protect equipment from moisture, but they organise your gear differently.
A large waterproof backpack liner creates one protected compartment for much of your pack’s contents.
Individual dry bags provide smaller waterproof compartments for selected items.
Neither option automatically replaces the other. The better setup depends on how you pack and what you need to protect.
When a Main Pack Liner Makes Sense
A main liner is a practical option for bulky equipment such as sleeping bags, insulating layers and spare clothing.
Instead of dividing these items between several separate bags, you can protect them together inside the backpack.
This keeps the system straightforward: insert the liner, pack your dry equipment and secure the closure.
If you’re also choosing a backpack or related equipment, explore Offtrack’s Packs & Bags range.
When to Use Additional Dry Bags
A main pack liner provides protection for your general load, but some equipment may benefit from being stored separately.
Phones, first-aid supplies, navigation equipment and other moisture-sensitive items may need their own protected compartments.
Using smaller dry bags alongside a main liner can help keep these items organised and provide an additional layer of protection where appropriate.
Separate Organisation From Whole-Pack Protection
Think of the main pack liner as your primary waterproof compartment.
Individual dry bags can then be used when you need quicker access, more organised storage or separate protection for particular items.
For example, keeping smaller equipment together can make it easier to locate without unpacking your entire sleeping system.
Offtrack offers a broader selection of Storage & Dry Bags for different packing requirements.
Use additional bags where they solve a specific problem rather than adding layers that make your pack harder to organise.
Waterproof Packing for School Camps and Expeditions
Group trips introduce another consideration: the packing system needs to be easy to explain and repeat.
When participants follow different methods, checking equipment before departure can become more difficult.
A simple approach is to establish clear expectations about which items belong inside the main liner and which should be stored separately.
For example, a group leader might require sleeping equipment and dry spare clothing to remain inside the main liner, with smaller items packed according to the group’s equipment requirements.
Offtrack works with student trips and outdoor expeditions, including gear-list support for groups preparing their equipment.
Check Your Pack Liner Before the Trip
The best time to identify a sizing or packing problem is before leaving home.
Load your backpack with the equipment you would normally carry and check how the liner fits inside the main compartment.
Pay attention to the shape of your gear, the way the contents sit against the fabric and whether the liner can be closed without difficulty.
This is particularly important if you’ve purchased a new liner or changed your packing system.
Test the Fit Before You Leave Home
Use this simple pre-trip check:
- Place the empty liner fully inside your backpack.
- Load the equipment you want to keep dry.
- Check that hard or sharp objects are not placing unnecessary pressure on the fabric.
- Make sure enough material remains above the contents to secure the closure correctly.
- Close the backpack and confirm the liner does not interfere with normal pack operation.
This gives you a better indication of practical fit than comparing litre capacities alone.
If your essential equipment only fits when the liner is packed beyond the point where it can close properly, review your packing arrangement or consider another liner capacity.
Also check the fabric and seams for signs of damage before relying on the liner during a wet trip.
Choose a Waterproof Pack Liner That Fits Your Gear
The right waterproof pack liner should protect your essential equipment without complicating the way you pack.
Start with your backpack’s capacity, consider the gear that needs to stay dry and check that the liner has enough room to close securely.
Construction and durability matter, particularly on longer trips where your equipment will be packed and unpacked repeatedly.
Offtrack’s Wilderness Equipment Pack Liners are offered in 60L, 80L, 100L and 120L capacities. They feature 70D nylon, seam-taped construction, a non-wicking drybag-style closure and a stated 10,000 mm waterproof specification.
These features make them worth considering when choosing waterproof protection for bushwalking, camping and outdoor expeditions.
Unsure Which Pack Liner Size You Need?
Backpack capacity is only part of the decision.
Your sleeping equipment, spare clothing, trip duration and packing method all influence how much liner space you need.
If you’re choosing between sizes, contact the Offtrack team with details of your backpack and the type of trip you’re planning.
We can help you narrow down the options before you head out.
Waterproof Pack Liner FAQs
Do I Need a Waterproof Pack Liner if My Backpack Is Water-Resistant?
A water-resistant backpack may provide some protection from rain, but that doesn’t mean moisture cannot enter through seams, zips or openings.
A waterproof liner creates a separate barrier around the equipment you need to keep dry, which is particularly useful during prolonged wet conditions.
Should My Pack Liner Be the Same Size as My Backpack?
Not necessarily.
Start with your backpack’s capacity, then consider how much equipment needs waterproof protection and whether the liner can close correctly once packed.
A litre-for-litre match may work, but internal pack dimensions and your packing arrangement also matter.
What Happens if My Waterproof Pack Liner Is Too Large?
A slightly oversized liner can often be folded and arranged inside the backpack.
However, too much excess material may make the load harder to organise or create unnecessary bulk.
Choose a capacity that accommodates your dry gear while fitting comfortably inside the pack.
Can I Use One Pack Liner Instead of Several Dry Bags?
Yes. A single main liner can protect sleeping gear, spare clothing and other equipment together.
Smaller dry bags are useful when you want to separate particular items, improve organisation or add another waterproof compartment.
What Should I Pack Inside My Waterproof Liner?
Prioritise equipment that needs to remain dry, particularly your sleeping bag and spare insulating clothing.
Depending on the trip, you may also want to protect electronics, navigation equipment or other moisture-sensitive items.
How Do I Close a Drybag-Style Pack Liner?
Leave enough spare material above the contents to operate the closure correctly.
Avoid overfilling the liner and follow the manufacturer’s instructions for securing the opening.
What Size Pack Liner Is Best for a School Camp or Multi-Day Expedition?
Start with the backpack sizes being used and the equipment participants are required to protect.
For group programs, a consistent packing method can make it easier to choose suitable capacities and check that every participant can secure their liner correctly.
