I just had that same situation to deal with this last weekend. I have the water stains and laundered them last year in Oxiclean and tide. They did not come out.
I was looking at them again to try a new approach. A while back I had bought "Instagone" from a TV promo. Although it did not mention using on fabrics I moved forward anyway. I got the drapes down, put them on a table with a towel between the fabric and liners, sprayed with Instagone. The stains disappeared almost immediately. I then stuffed the drapes into the washer and washed them with oxiclean and tide again and dried them. The look great. No more water stains and nice clean drapes.
