I currently run the RO water through a calcite filter to raise the pH and improve taste. I read a post on a home brewing forum in the home seltzer making section, where this mineralization filter outperformed bottled water and other filters inboth still and carbonated water for taste. Being that I like the taste of mineralized water, especially in coffee, as you mentioned, it seemed like a worthwhile experiment to try it for myself.An interesting project, and some unusual issues to overcome. Certainly, I agree, natural (mineralized) spring water from a karst area makes excellent coffee or drinking water. Our water tested below limits for lead and cadmium (we are in a mining area), but we installed an RO in our house rather than take a chance on an unexpected change. Would be interested in hearing how well your arrangement works out.