Not all waterproof backpacks are sustainable, it all depends on the materials.
8000Kicks backpacks are waterproof and sustainable because they were built that way. The outer hemp fabric has a bio wax soy coating that repells liquids from coming in. Then we have added a waterproof membrane that keeps liquids out no matter what. This membrane made of PU, a synthetic material used to make vegan shoes.
No PFCs, teflon or other harmful toxic quimicals was used to make our backpacks waterproof.
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Hemp is also very ecological:
-it consumes 5x less water than cotton
-It restores the nutrients in the soil
-it needs not fertilizers to grow
-it captures CO2 from the atmosphere