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What is a drainable bulk bag, and when would I need one? Well, if you are reading this blog post, you may be in need of bulk bags for draining purposes, or killing some time educating yourself on FIBC options (and we are glad you chose to do so here!)

Most bulk bags have the opposite goal of a drainable bag: they are designed to contain material, and not permit material to pass through the fabric whether inside-to-out or outside-to-in. A draining bulk bag or dewatering bulk bag would differ, in that its goal is to permit the egress (draining) of liquid that gets into the bag, while also not permitting the loaded material to pass through and self-discharge. Materials that are sludgy, hydrophilic, or covered in water during bag fill are common candidates for a drainable bulk bag.

Unlike barrier liner bags, where there are multiple levels of moisture & oxygen resistance against ingress (coating & siftproofing, PE liners, EVOH, foil liners, etc.), there are two primary drainable bag options, which are uncoated bags, and dewatering bags.

Uncoated bags are the entry level of drainable FIBC options. An uncoated bag means that the woven polypropylene fabric used to make the bag is NOT manufactured with a thin coating of polyethylene (coated fabric). This leaves the weave permeable through the natural gaps that woven fabric leaves. This option is suitable for loose or bulky materials (wet recyclables/ construction debris / wet stone, etc.) that are being loaded wet into a bag and would have water pooling at the bottom. Uncoated fabric (pictured below) permits water to seep through at a slower rate and would not permit significant venting.

A Dewatering Bulk Bag (pictured below) is the ideal performer when discussing drainable FIBC options. Dewatering bags are constructed with a specially woven fabric with sections of open weave, allowing large pass throughs where water can drain from the material inside of the bag. The size of the openings in the fabric is enough where you also get fair ventilation properties, helping material dry out inside of the bag, while also not being so big where the material itself will pass through. This is a great option for sludge, silt, and sediment, and cakey material.

The determining factor on what style of bag you would need depends on the amount of moisture needing removed from the material, how said moisture bonds with your material, and how quickly it needs to get out. To help find which option would best fit your project, contact our team or request a quote for more information!