Unlike less durable bags, bulk FIBCs are made from woven polypropylene. This hard-wearing plastic offers the perfect balance of durability and flexibility. These woven bags are robust enough to be filled with incredibly heavy loads and can be easily transported long distances. However, the woven construction of these bags means they’re not inherently waterproof.
That being said, you can improve the watertight and waterproof credentials of a bulk bag. Using a polyethylene liner is a good way of preventing moisture from damaging the contents of a ton bag. This thin layer of plastic can be added to the inside or outside of a bag. While this can serve as a water-resistant barrier, it’s not entirely waterproof.
Although polypropylene itself is waterproof in its non-woven form, woven polypropylene is more permeable. The looser the threads, the less waterproof the material becomes. Many FIBC manufacturers add laminate polymer to polypropylene to compensate for this. While this can go a long way in filling the microscopic spaces between threads, it’s impossible to make the material completely watertight. Furthermore, this process has some downsides. If you’re looking for a breathable FIBC bag, bulk packaging treated with a polymer coating isn’t a good idea.
Different bag closers can also play a part in how watertight or waterproof a FIBC is. Some ton bags come with a drawstring top that can be closed securely once a container is filled. However, they’re not particularly practical. A more functional alternative is a bulk container with a flat top. Once filled, a separate piece of fabric can be placed over the top and held in place with button or snap fastenings.
Although FIBC big bags are not completely waterproof, you may encounter designs being marketed as water-resistant or waterproof bags. Water-resistant bags have usually been treated with a polypropylene coating. Although this coating is invisible to the naked eye, it typically leaves the surface of a bulk bag feeling smoother and gives it a noticeably glossy finish. This coating serves to seal gaps in the woven material, creating a less permeable surface. However, the water-resistant fabric won’t keep every last drop of water out, especially if a bulk bag has been stored outside without a secondary covering.
Ultimately, coating only offers minimal protection against the elements, even if it’s effective at staving off moisture and dust. If you’re looking to keep moisture intrusion to an absolute minimum, it’s best to invest in waterproof FIBC bags. Once again, these container bags aren’t truly waterproof, but they’ll feature several properties that make them more resilient to environmental factors.
FIBCs marketed as waterproof will also have been laminated with a polypropylene layer. In the case of waterproof bags, this film layer should be thicker than what you’ll get from a water-resistant container bag. Sometimes, these designs are sold as non-breathable FIBCs. Even these high-quality bags need a helping hand to lock out moisture. You’ll often find them being sold with additional liners. These liners can be removable, while other bags may come pre-lined.
| Feature | Water-Resistant FIBC Bags | Waterproof FIBC Bags |
|---|---|---|
| Coating type | Standard laminated polypropylene coating | Heavy-duty laminated polypropylene coating with PE liner (removable or fitted) |
| Coating thickness | Thin protective laminate | Thicker laminate with additional moisture barrier |
| Breathability | Moderate – some airflow retained | Low – typically non-breathable to maximize moisture protection |
| Moisture protection level | Protects against light rain, dust, and humidity | High protection against heavy rain, prolonged moisture exposure, and water ingress |
| Recommended use case | Dry powders, grains, fertilizers, agricultural products, indoor storage, short-term outdoor use | Food-grade products, chemicals, moisture-sensitive powders, pharmaceuticals, export shipments, extended outdoor storage with additional protection |
| Price tier | $ (Lower cost) | $$–$$$ (Higher cost due to thicker coating and liners) |
Owing to their robust construction and versatility, FIBC bags are widely used across many different industry sectors. They’re a popular sight in agricultural settings. FIBCs can be used to store and transport freshly-harvested produce, dramatically extending its shelf life. Just about every type of foodstuff can be stored in a bulk bag, from fine powders and grains to root vegetables. In these cases, breathable bags are best. However, when it comes to storing and hauling livestock feed, bags with water-resistant properties are something to consider.
They’re also a common sight in the food processing sector. Food-grade FIBCs can be used to safely handle processed goods, while fully-loaded bags can be easily stacked and lifted in warehouse settings. What’s more, bulk containers can be readily adapted with different filling and discharging features.
FIBCs are also used in the construction industry. Bulk bags are convenient for storing and transporting construction materials, as well as allowing for safe handling of debris and hazardous materials.
Type C FIBC bags are regularly used in the chemical manufacturing industry. Boasting conductive properties, these bags are suitable for use in potentially dangerous environments where static electricity is a concern. You’ll also encounter bulk containers in the mining industry. Their heavy-duty capacity makes them ideal for hauling bulky ores, minerals, and coal, while their durable construction ensures they’re a cost-effective choice.
Although storing FIBC bags outside isn’t advisable, there are many steps you can take to ensure they’re better protected against the elements. Ideally, you should only be considering outdoor storage if you’re using newer FIBC jumbo bags. The newer your container bag is, the less likely it is to have superficial damage. Furthermore, the woven construction of a newly manufactured bag will be in much better condition than one that’s been used several times before. A fresh coating will also provide added protection against water and the elements.
To bolster protection against water and external factors, it’s also worth investing in a bag liner. These liners provide an extra layer of protection against moisture, helping keep your bulk bags watertight. FIBC bags come in many varieties, but it’s best to choose a design with duffle and spout-style tops. Although these tops won’t make bags waterproof, they’re far more effective at keeping moisture out than open-top designs.
Another way to keep your bag waterproof is to keep it covered with weather-resistant material. An inexpensive tarp can form a reliable barrier against rain and UV rays. Ultimately, however, outdoor storage should be seen as a temporary solution. Ideally, you should be aiming to secure an indoor storage location as soon as possible.
Outdoor storage should be treated as a temporary measure. Before moving filled FIBCs outside, confirm that the bag design, liner, closures, and stored material are suitable for the expected weather and temperature conditions.
Use an industrial-grade weatherproof tarp. Choose a waterproof, UV-resistant polyethylene or PVC tarpaulin with reinforced edges and enough material to cover the top and sides of the bags. Pitch the tarp so rain and melting snow run off instead of collecting on top. Secure it against wind without tying straps directly around the bag or its lifting loops, and leave enough airflow to reduce condensation beneath the cover.
Store bags on a raised, load-rated base. Do not place filled FIBCs directly on soil, gravel, or any surface where water may collect. Use clean, level, load-rated pallets, dunnage, or another raised platform that supports the complete base of each bag. Inspect wooden pallets for broken boards, nails, splinters, and other sharp edges that could puncture the fabric.
Plan for drainage. Select firm, elevated hardstanding and keep bags away from low points, downpipes, flood routes, and drains that may overflow. The surface should direct water away from the storage area, with no standing water beneath the bags. Leave sufficient space between rows for drainage, inspection, and safe handling. If the contents could harm the environment, provide appropriate secondary containment and follow local site and regulatory requirements.
Limit exposure to sunlight and severe weather. UV-stabilized fabric can still deteriorate during prolonged outdoor exposure. Inspect the tarp, bag fabric, seams, closures, and lifting loops after storms and at regular intervals. Remove accumulated water or snow from the cover safely. Do not lift a bag that shows tearing, brittle fabric, damaged stitching, or weakened lifting loops.
Avoid unsupported stacking. Store bags in a single layer whenever possible. Only stack FIBCs that are designed and approved for stacking, and use a stable pyramid or properly supported stacking arrangement.
Check freezing risks for liquid products. Standard FIBCs are designed for dry, flowable solids—not free liquids. Liquids should only be stored in a flexible liquid container, composite IBC, or other package specifically rated for the product and expected temperature. Before outdoor storage, check the liquid’s freezing point, the container’s minimum temperature rating, required ullage, and the cold-temperature rating of its liner, valves, and fittings. Move the container to temperature-controlled storage or use manufacturer-approved frost protection before freezing conditions arrive. Never use an open flame or unapproved direct heat to thaw a container, and do not lift or discharge a frozen container until the supplier confirms that it is safe.
Inspect and document outdoor exposure. Record when each bag was moved outdoors and inspect it after heavy rain, high winds, snow, freezing temperatures, or damage to the tarp. Relocate the bag indoors if its cover fails or there are signs that moisture or weathering has affected the packaging.
1. How long can FIBC bags be safely stored outdoors?
Outdoor storage should be considered a short-term solution. Even with protective measures, prolonged exposure to UV rays, moisture, and temperature fluctuations can degrade the material and reduce load capacity over time.
2. What are the risks of prolonged UV exposure on bulk bags?
UV exposure can weaken polypropylene fibers, causing discoloration, brittleness, and reduced tensile strength. Over time, this increases the risk of tearing or failure during lifting and transport.
3. How should businesses plan storage during seasonal weather changes?
Companies should adjust storage strategies based on seasonal risks, such as increased humidity in winter or UV exposure in summer. This may include rotating inventory more frequently or using temporary covered storage solutions.
4. Can outdoor storage affect the safety rating of FIBC bags?
Yes, environmental exposure can compromise the structural integrity of bulk bags, potentially affecting their safe working load (SWL). Bags stored outdoors should be inspected thoroughly before reuse.
5. When should an outdoor-stored FIBC bag be taken out of service?
A bag should be retired if there are signs of fading, fiber weakening, tears, compromised stitching, or reduced structural integrity. Any visible degradation can indicate that the bag is no longer safe for handling heavy loads.
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