To protect against dangerous waterborne germs, many individuals, including healthcare facility managers, opt for antimicrobial showerheads that contain silver. However, new research published in ACS ES&T Water indicates that these showerheads may not be the ultimate solution. Under actual showering scenarios, many germs do not remain in contact with the silver long enough to be effectively eliminated. Interestingly, the study found that the types of rare microbes present in the water from these showerheads differed depending on the specific model tested.
To protect against dangerous waterborne germs, many individuals, including healthcare facility managers, opt for antimicrobial showerheads that contain silver. However, new research published in ACS ES&T Water indicates that these showerheads may not be the ultimate solution. Under actual showering scenarios, many germs do not remain in contact with the silver long enough to be effectively eliminated. Interestingly, the study found that the types of rare microbes present in the water from these showerheads differed depending on the specific model tested.
The droplets and mist created during a shower can be breathed in or swallowed. Installing silver-infused showerheads—silver being a naturally antimicrobial metal—is a budget-friendly strategy to potentially safeguard against pathogens found in drinking water (DWPIs). Such pathogens, including strains of Pseudomonas and Legionella, can infect individuals with weakened immune systems. However, prior studies have shown that the addition of copper and silver to a building’s water system to combat bacteria and viruses (known as copper-silver ionization) provides only a temporary or minimal solution. There is a growing concern within the scientific community that short-term exposure to silver in showerheads could actually enhance microbial resilience and heighten antimicrobial resistance risks instead of reducing them. To investigate this, Sarah-Jane Haig and her team aimed to determine how silver-containing showerheads impacted the microbial makeup of the water.
The researchers examined two standard showerheads made of either plastic or metal, alongside three models that included silver—one with silver mesh within the fixture, another featuring a silver-coated copper mesh in both the showerhead and hose, and the last being a silver-embedded polymer composite. The showerheads were tested in Haig’s advanced shower lab, which was designed to replicate real-life conditions.
In a surprising twist, the researchers found that silver did not lower the levels of DWPIs or total bacterial counts in the water samples collected from the testing environment. Haig and her colleagues attributed this lack of effectiveness to differences in testing methods when compared to those used by manufacturers. Specifically, the water flowed rapidly from the showerhead during the study, mimicking actual showering experiences. In contrast, standard manufacturer tests often involve exposing microbe cultures to the silver for a duration of 16 to 24 hours, which the researchers deem unrealistic.
While the overall levels of pathogens in the water remained consistent between standard and silver showerheads, the analysis revealed differences in the composition of the microbiome. Each type of silver-containing fixture harbored different microbial populations, indicating that the method of incorporating silver into the showerheads made a significant difference, with rare microbes contributing predominantly to these variations. Additional findings suggested that the microbes present in the silver-infused showerheads might be more inclined to develop microbial communities known as biofilms, particularly when faced with challenging conditions. These biofilms could explain the relationship between the number of diverse species and the age of the showerhead, as they serve as reservoirs for DWPIs.
“These findings highlight the urgent need for better testing standards, thorough evaluations of real-world performance, and innovative strategies to reduce microbial hazards in water systems for the protection of consumers and at-risk groups,” remarks Haig.
The authors express gratitude for financial support from the National Science Foundation.
