Which Bacteria Are There?

• Swabs of shower heads across the U.S. revealed Mycobacterium avium at levels about a hundred times higher than in normal water conditions.
  
  

What Does It Do?

• The health risks associated with this bacteria are not completely clear. Most infections involving this microbe are found in people who already have compromised immune systems or chronic lung diseases.
  
  

What Is the Risk to Me?

• The risk probably is low. It is not yet clear how much of the bacteria actually come through the shower head when water is flowing. If you have a serious lung disease, you may wish to be careful.
  
  

What Can I Do?

• If you have an old shower head, check to see if it is full of grime. This grime contains the bacteria, so you might want to replace a grimy shower head.
  
  

What Shower Heads Are Best?

• The same study has shown that all metal shower heads are better than ones with plastic parts, because the bacteria are better at sticking to plastic surfaces.