I’m in the process of developing a 4FreshWater backpack. I first got interested in doing this because I came across a material called Tyvek, which is 100% recyclable and waterproof. I thought it would be a great idea to make a backpack out of it to sell and then donate the profits. Here is some information on Tyvek,

https://www.dupont.com/tyvekdesign/design-with-tyvek/tyvek-sustainability.html

https://www.dupont.com/products-and-services/fabrics-fibers-nonwovens/protective-fabrics/brands/tyvek/articles/tyvek-advancing-sustainability.html

And here is a EARLY mockup of the backpack design.