I tried to find a waterproof curtain for the window above our bathtub.  We usually take showers and water would get in the window sill and also get on the cloth curtain.  I wanted to keep water out of the window sill but could not find anything suitable to prevent that from happening.  I finally thought of buying an inexpensive vinyl shower curtain liner and I made my own curtain out of it.  The vinyl is so soft and almost cloth-like.  I cut off the top of the shower liner (with the holes) so the bottom part of the liner would be the length I wanted for the window curtain.   I added two and a half extra inches to allow for the curtain rod insert pocket which would be at the top of the window curtain.  (The thin pressure type rod works great, by the way.)   I simply folded down the top of the new window curtain one and a half inches to form the rod insert pocket.  I used button thread to make simple stitches to make the pocket.  If your sewing machine isn’t in the attic like mine then you could probably just stitch it on the sewing machine.   It’s very simple to make and you don’t have to hem the very bottom or sides of the curtain.   We’ve been using the new curtain for several months now and it works great and looks fine!