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We’ve become a rather germ-phobic society, what with our antibacterial soaps, hand sanitizers, automatic water faucets and self-flushing toilets — all of which are supposed to reduce our contact with potential disease-causing bugs. But it turns out that at least one pathogen-fighting strategy may actually be exposing us to more germs, rather than fewer.

Researchers at Johns Hopkins Hospital conducted an eye-opening study on the bacterial growth within two different kinds of taps — hands-free, automatic faucets activated by an electronic eye, and the old-fashioned manual type that users have to turn in order to start the flow of water. About 50% of the water samples from the electronic faucets tested positive for legionella and other bacteria, while only 15% of the samples from the manual faucets did.

But before you start looking askance at all the hands-free faucets in public restrooms, the study’s co-investigator, Dr. Emily Sydnor, a fellow in infectious diseases at Hopkins, notes that the growths she found would not pose a health risk for most healthy individuals.

Yes, the automatic faucets harbored more bugs than the manual ones, but that doesn’t mean they’d make you sick. The water samples were taken from faucets located all over the hospital, including patient rooms, and no patients reported infections from the water.

Still, in a hospital setting, the findings could be cause for alarm. That’s because hospitalized patients are more likely to have compromised immune systems, whether they are being treated for cancer or undergoing an organ transplant. That’s why Hopkins officials decided to play it safe and go back to manual faucets in a new building under construction on campus that would include patient rooms.

“The electronic faucets are in the process of being removed and the plan is to remove them from the existing hospital as well,” says Sydnor. “And the order for 1,000 to 1,100 electronic faucets for clinical and patient care areas in the new building was recalled based on these findings.”

Why are the automatic faucets so bug-friendly? Gregory Bova, senior engineer at the hospital, says it’s the plumbing. While the plumbing for manual faucets is relatively straightforward, with a pipe each for hot and cold water feeding into the faucet, hands-free models are more complex. They include various valves, screens and filters designed to prevent backflow of hot or cold water to the wrong pipe, and all that machinery provides the perfect nesting ground for bacteria and other pathogens.

Sydnor and Bova both acknowledge that the results surprised them. They never expected that the hands-free faucets would contain more bacteria than the manual ones. In fact, their study started out as a way to determine how often they should program the automatic faucets to run in order to flush out colonies in case they weren’t used often enough. It turns out the faucets were never that idle, but that they were a fertile location for legionella to take hold.

Still, the amount of bacterial growth the researchers found wasn’t enough for them to shun electronic faucets in public restrooms: in the public, non-patient care areas of the hospital, Sydnor and Bova say they’re keeping the automatic model.