I too have very hard water. For both color and b&w processing I find it necessary to use film sponges and carefully remove the excess rinse even when using distilled water for the photoflo last rinse following the wash. If I remove as much as possible leaving only a few drops, then I get a clean dry and have had no problems with debris or scratching. You must use very clean carefully stored photo-grade sponges moved slowly down the film following both sides, usually in two passes to eliminate drops. My sponges are wetted with either photoflo or stabilizer (I usually use stabilizer for b&w too), and then sqeezed out as much as possible before wiping the film to dry.
Using distilled water or stabilizer alone and leaving the film to dry is not sufficient because there are water spots left from the few places where the film surface retains moisture. However, I never got drying spots on the emulsion side; only on the film base. In the old days when there was a drying mark on the film base that would show up in printing, the news-room cure was "nose grease." Anybody else remember those days?