Sorry I don't have an answer, but I am working on this myself. I have consulted with several water people and no answer yet. Your description of the problem, is the first time in a year of searching, that sounds exactly like mine, including the pink stain and everything else, toilets ets. Its now even in our ice cubes. I like you am highly allergic to mold and do suffer from frequent sinus headaches. Let me know if you hear anything and vice versa.