Coming clean: Your showerhead is spritzing bacteria on your naked body

November 7, 2018

Do you want to know “the real dirt” on showers? A study conducted at the University of Colorado-Boulder has found that showerheads are covered with bacteria-filled slime that could make us sick.

The researchers used high-tech instruments and lab methods to analyze roughly 50 showerheads from nine cities—among them, New York City, Chicago, and Denver—in seven states nationwide.

They concluded that—while we believe we are getting invigorating relief and a good daily cleansing, about 30% of the showerheads we use instead are covering our naked bodies with significant levels of Mycobacterium avium. That’s a pathogen linked to pulmonary disease that most often infects people with compromised immune systems; but which occasionally can infect healthy people, said CU-Boulder Distinguished Professor Norman Pace, lead study author.

 “If you are getting a face full of water when you first turn your shower on, that means you are probably getting a particularly high load of Mycobacterium avium, which may not be too healthy,” he said.

Showering may cleanse our bodies of sweat and dirt, but over time, our showerheads develop scum—also known as biofilm—due to the warm, wet conditions in the stall or tub.

Many of the bacteria in the scum are not harmful, but the team did find traces of nontuberculous mycobacteria (NTM) in showerheads across the United States. NTM is particularly prevalent in parts of Southern California, Florida, and New York — all areas with higher reported incidences of NTM lung disease, the study authors note. They believe showerheads may transmit the disease.

Symptoms of the infection include coughing up blood, shortness of breath, persistent coughing, fatigue and fever, according to the American Lung Association. Not everyone develops the condition after exposure to NTM, and doctors aren’t sure why only some people get sick. However, those who already have lung problems,  as well as older adults and people with weak immune systems are at greater risk. The infection is treated with antibiotics, according to WebMD.

The team also found that NTM is more common in metal showerheads, as well as U.S. households that use municipal water over well water. Mycobacteria are resistant to the chlorine found in municipal water, so they have more room to grow after other the chlorine kills off other bacteria.

According to study co-author Noah Fierer, more research should be done to determine whether our water treatments could put us at risk.

“There is a fascinating microbial world thriving in your showerhead and you can be exposed every time you shower,” Fierer said in a statement. “Most of those microbes are harmless, but a few are not, and this kind of research is helping us understand how our own actions—from the kinds of water treatment systems we use to the materials in our plumbing—can change the makeup of those microbial communities.”

What does all this mean for you? You definitely shouldn’t stop showering, but you might want to think about cleaning your showerhead every now and then. Using vinegar, which has been shown to kill many types of mycobacteria, is a good bet.

Research contact: matthew.gebert@colorado.edu

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