Recent research found that mycobacterium avium lives in the majority of showerheads tested...

http://www.reuters.com/article/lifes...58E03U20090916

Heard Dr Pace interviewed on NPR and he found that plastic showerheads/ plumbing harbored a significantly higher level of pathogens than metal showerheads/plumbing. The interesting part to me, as an aquarist, is that copper is an effective antipathogen in aquariums, to the point where it can kill not only parasites but also corals and invertebrates. Perhaps copper plumbing is not only efficient, but it also protects our health ?