I'm new to this site and appreciate all the input from those contending with this disease! It's my understanding that the MAC exists in the showerhead itself. I was told to dismantle the showerhead once a week and soak it in vinegar. What I also read is that copper kills bacteria. Therefore, I replaced my shower hose and showerhead with copper. The hose is copper infused and the showerhead is solid copper. It's easy peasy to unscrew the head after every shower and drain it and let it air dry, also. I hope this helps! Tonni