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Bulk bags are some of the most durable and versatile packaging solutions available as they can be used to store a vast array of materials. Sometimes, these include viscous materials, so the woven fabric of the bulk bags needs to be somewhat waterproof. 

Many bulk bags can be ordered with a splashproof lining to prevent moisture from entering through the pores in the fabric, but some materials need a more watertight fabric. Custom Bulk Bags (CBB) is a leading manufacturer and supplier of bulk bags, so speak to one of our consultants before placing an order and we can ensure that your needs are met.

CBB is able to produce bulk bags of varying dimensions and load capacities. However, we are also able to completely customise orders with various optional extras such as splashproofing and inner liners. Many customers may wonder how effective these qualities may be for liquid materials.

Water drops on surface of black woven fabric

Are bulk bags utterly waterproof?

Due to the nature of the woven polypropylene fabric used to make bulk bags, they are not completely waterproof in their basic form. There are small holes in between the tapes of polypropylene through which water and liquid materials can escape. This is why some bags need to be treated with a splashproof coating to protect any powdered or water-soluble materials within. 

This laminate coating is sprayed onto the fabric to seal the minute holes, however, some of the gaps may remain open. This is why we refer to it as splashproof, not waterproof. This coating works well to protect dry materials from excess moisture seeping through the fabric, but it will not be enough on its own to store viscous or liquid substances.

Water droplets on surface of black woven fabric

Optional extras to improve water resistance

Although basic bulk bags are not waterproof, there are some optional extras that you can order to make them more watertight. A polyethylene liner is probably the most effective way of protecting water-soluble materials or for storing viscous materials without them leaving through the bulk bags. 

This liner is a thin sheet of plastic that can be inserted inside the bulk bag and it creates a more watertight barrier. These liners can be removable or ordered as a pre-lined bulk bag. It’s important to note that these liners do not make bulk bags 100% waterproof, but they are highly effective for storing viscous substances, such as oils, for certain periods of time. 

Some of the bulk bag closures also help to improve water resistance – the most common type being the drawstring closure, which includes a piece of string to keep the closure tightly sealed. Flat tops and valve tops are also effective at creating tight seals and adding an extra layer of protection for powdered substances.

This is why it’s important to speak to an expert before placing a bulk bag order. Our consultants will be able to give you guidance and advice on the best solutions for making your bulk bags more waterproof. For more information about our bulk bags, please contact us today. 


Custom Bulk Bags is a leading South African manufacturer of woven polypropylene bags for various industries, such as mining, chemicals and food. We are able to produce over 3.5-million bulk bags per year, keeping our customers in stock at all times. Our bags adhere to the highest levels of quality as a result of our stringent in-house testing and quality control programmes.

Custom Bulk Bags holds ISO 9001 certification and we currently have a number of UN-certified designs. We are a Level 3 B-BBEE manufacturer and supplier and fall under the ownership structure of Deneb Investments Limited. For more information on our products, contact Follow us on Facebook for our latest news and industry insights.