Book review by Robin Marantz Henig of NY Times of nonfiction work "Never Home Alone" by Prof. Rob Dunn of Applied Ecology at North Carolina State University sheds new light on microbial fauna that inhabit dwelling areas and on showerheads.
It's reported, "As the water passes through the showerhead, these microbes lay down a kind of scaffolding known as biofilm to protect themselves from getting washed away with every ablution." They make the biofilm “out of their own excretions." "Filtered through that poop-biofilm, the water that washes over you, as you supposedly scrub yourself clean, might contain not only all those harmless amoebas and nematodes but a few bacteria that can be dangerous — in particular some species of Mycobacterium, cousins of the Mycobacterium that causes tuberculosis. And the pathogens are there because we provided the perfect breeding ground for them, when we tried to purify our tap water in the first place. Municipal water treatment plants use chlorine and other chemicals that kill off the bacterium’s natural predators, allowing Mycobacterium to thrive. Tap water that comes from a well, in contrast, has never gone through a treatment plant and has a rich microbial life. It might look more dangerous, but it’s actually safer, Dunn explains. All those organisms in well water are themselves harmless, and they tend to fight off the potentially dangerous ones like Mycobacterium — that’s how biodiversity works"
The author is reported to say that "we might want to change the showerhead a little more often — and consider switching from metal to plastic, where biofilm is less likely to accumulate. Nonetheless, his bottom line for showerheads is like his bottom line for other aspects of the roiling microbial mix we live in: Don’t be afraid of letting life inside. “The water that is healthiest for bathing is that which comes from aquifers rich with underground biodiversity including crustaceans,” he writes. “The crustaceans in these aquifers are an indication not of the dirtiness of the water but of its health.
Consider changing showerheads often, and while you're at it, might as well install low-flow heads and shower timers. Conservation is the key. Wouldn't you agree?