I would lightly spray the back of it with either Scotchguard or the new Multiwet repellant by rustoleum. They make one for fabrics now. They say you can even put regular fabrics sprayed with this outside. That way if the back gets wet the water won't penetrate the fabric. I have to make my shower curtains because I have a walk in shower that replaced the tub and it needs 72 x 78 which you can't find except in the vinyl liner. I use curtains that I sew together and then hem and place button holes across the top about every 6 inches. Works great especially when I can get curtains on clearance for $2 - $3 a panel. And I do use a liner behind it.