Shower Risks: Microbes, Water Quality, and Safety Tips

You may think you’re alone in your shower, but research shows it’s a popular gathering spot for microbes.

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Eight minutes a day. That’s the average duration of our daily cleansing ritual—a time to rejuvenate, exfoliate, and breathe moisturized air. You’ve likely never thought these precious minutes may expose you to unwanted bacteria and microbes, but they can.

The Unseen World of Your Shower Head

Shower heads are an almost ideal habitat for microbes. The conditions of dampness, warmth, and darkness—along with trace nutrients and organisms—encourage microbes to form resilient biofilms that can withstand standard sterilization methods and resist antimicrobial treatments.

A study by the University of Colorado–Boulder examined 45 shower heads across nine U.S. cities, employing cutting-edge molecular techniques to identify resident bacteria. The researchers concluded, “Showerheads may present a significant potential exposure to aerosolized microbes.”

Researchers discovered a specific bacterium called Mycobacterium avium, a non-tuberculous mycobacterium (NTM). Its concentration in some shower heads was 100 times that of the regular water supply. It appeared in 20 percent of the tested samples, and the detected rate was 78 percent with more advanced testing methods.

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NTM primarily affects those with weakened immune systems. According to NTM Info & Research, in the United States, as many as 220,000 people have NTM lung disease, a figure that’s rising by 8.2 percent annually in people older than 65.

Joseph O. Falkinham III, a leading microbiology professor at Virginia Tech, told The Epoch Times that the groups most vulnerable to NTM disease are smokers, people with chronic obstructive pulmonary disease, people with lung damage from particulates, and people with weakened immune systems, including HIV patients. Notably, tall, slender, older females also face increased risk, he said.

The symptoms associated with NTM infections can be serious. Chronic or recurring coughs, night sweats, weight loss, and persistent energy loss are just some of the indicators.

Showers release water droplets and steam that may carry NTM into the air. Although these bacteria commonly exist in environments such as soil, their effects can become more harmful when they’re aerosolized by the shower.

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Norman Pace, a study author from the University of Colorado–Boulder, sheds light on this in a 2009 interview on Talk of the Nation, explaining that these bacteria are opportunistic pathogens. They’re ubiquitous in our environment but usually harmless. The problem with showers, he says, is how they deliver these organisms. Showers produce fine aerosols, many smaller than 20 micrometers that can travel into our lungs, bearing bacteria from the shower head.

Chlorine doesn’t deter NTM bacteria. A 2018 study found that U.S. homes connected to municipal water supplies registered mycobacteria levels more than double the levels in homes on well water. Interestingly, the study underscored a material distinction—these bacteria showed a marked preference for metal shower heads over their plastic counterparts.

From Tap to Tub—The Water Quality Conundrum

Many prioritize filtering drinking water but give little thought to the water from our shower heads. Yet research suggests that certain chemicals in our water can enter our bloodstream more swiftly through inhalation and skin absorption during showers than from drinking directly.

Chlorine is used as a trusted tool to purify our water, targeting harmful bacteria and ensuring that water is safe to consume. But there’s a flip side to chlorine once it reaches our homes.

When heated, chlorine can transform and vaporize into a form inhaled while showering. This direct lung exposure could have implications different from those of drinking the same water.

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Chloramines, created from the mixture of chlorine and ammonia, are a disinfectant used in many city water treatments. They linger longer than their chlorine-only counterparts and help reduce harmful byproducts.

The U.S. Environmental Protection Agency (EPA) has generally deemed such volatile organic chemicals (VOCs) as safe. They state that water containing chloramines, adhering to the regulatory standard of up to 4 mg/L, is suitable for drinking, cooking, bathing, and other household uses.

Dr. William Davis, a renowned cardiologist and author, suggested that the EPA recommendations may not be grounded in comprehensive research.

“Chloramine, unlike its counterpart chlorine, exhibits a stubborn resilience,” Dr. Davis said. “While chlorine can be eliminated through boiling, chloramine lingers, requiring as much as four days to dissipate.”

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He said that exposure to chloramine during showers may be linked to some health ailments, from dermatological conditions to gastrointestinal disruptions, and that repeated contact can intensify respiratory problems such as lung irritation and bronchitis, leading to symptoms such as coughing and breathlessness.

Other preliminary studies associate prolonged VOC exposure with the aggravation of respiratory conditions such as asthma and with potential DNA damage, which was observed in animal tests.

Mold: The Unwanted Guest

Where water finds a haven, so does mold—especially in our bathrooms—the epicenters of water use. Those black speckles in the grout of our shower walls or the yellow-green discoloration of the shower curtain may indicate the presence of mold, which can release microscopic spores into the air.

Mold spores, when inhaled, can pose health concerns, particularly for those with allergies, asthma, or compromised immune systems. Symptoms can range from nasal stuffiness and throat irritation to skin rashes and aggravated lung illnesses.

Certain mold varieties, such as black mold, produce mycotoxins—toxic compounds that can adversely affect human health. Long-term exposure can exacerbate respiratory problems, disrupt mucous membranes, and have neurotoxic effects, leading to memory loss or cognitive impairment.

The INHALE Lab’s Pursuit

Inside a 250-square-foot lab at the University of Pittsburgh, nine shower heads operate daily, serving as a testing ground for understanding the microbes present in our showers. The central question: How do different design aspects influence the concentration of drinking water-associated pathogens in shower water and the aerosols it produces?

Janet Stout, an authority on infectious disease microbiology and the president of the Special Pathogens Laboratory, elucidated the project’s mission: “The INHALE lab will help us understand the microbes in our showers, how they’re disseminated, and most importantly, how to control them, under conditions that replicate your own shower.”

Offering a clinical perspective, Dr. Janet Lee, chief of the pulmonary and critical care medicine division and a co-principal investigator of the study, said, “This knowledge will empower individuals to select shower heads that prioritize their health.” The study’s insights promise a cleaner shower and a healthier future for its users.

Beyond Cleanliness: Prioritizing Health in Your Shower Routine

To keep your daily cleanse refreshing, follow these essential guidelines:

Care For Shower Heads

• A monthly overnight soak of your shower head in white vinegar and water solution can help reduce bacterial buildup.
• Replace old shower heads every few years to minimize the risk of pathogen accumulation.
• Replace fine mist shower heads with ones that have larger holes, preferably greater than 1 millimeter in diameter.
• Opt for shower heads that are easy to dismantle and clean, reducing hidden nooks and crannies where microbes can thrive.

Disinfect Shower Heads

According to Mr. Falkinham, the best approach to cleaning and disinfecting a shower head includes:

• Unscrew the shower head.
• Clean the inside as well as possible with a swab.
• Submerge the shower head in a bucket with a 1:10 solution of detergent (he recommends Dawn) and water for 10 minutes.
• Follow with submersion in a bucket with undiluted bleach for 30 minutes.
• Remove from bleach and rinse the shower head thoroughly before reattaching it.

Improve Water Quality

• Consider installing a water filter designed for showers. These filters can reduce the concentration of harmful chemicals and pathogens.
• If your water comes from a municipal source, familiarize yourself with the water treatment methods. This knowledge can guide you in choosing the right filter.
• Periodically test your shower water, whether you rely on a well or a municipal source.
• Consider cold showers, which can reduce the vaporization of VOCs.

Eliminate Mold

• Ensure proper ventilation in your bathroom to minimize mold growth. Use exhaust fans or open windows, especially after hot showers.
• Regularly clean tiles, grout, and other surfaces with a mold-killing solution.
• Check for and promptly repair any leaks. Persistent dampness is a magnet for mold proliferation.
• Use a squeegee or dry cloth to wipe dry your shower and shower curtain after showering.
• Use a shower curtain liner that can easily be replaced if it shows signs of mold.