Over a 10-14 day period, blue/purple stains develop in the bottom of our toilet bowl. The tank is crystal clear. They do not form in our other toilet. We have soft water. Where are the stains coming from and how can we prevent them from forming?
Here is a possiblity, my mother takes medicine for urinary infection and so forth, the pills, leave blue residue, so if other folks are using your toilet, then maybe. If not cleaned normally, there will be lot of blue.