March 31, 2011 at 8:22 AM ET
Sorry, germaphobes: Those hands-free, automatic faucets that seem so clean and germ-free might actually be housing more bacteria than the old-fashioned, manual kind, according to a new Johns Hopkins University study.
Researchers, led by Dr. Emily Snydor, tested electronic and manual faucets in patient care areas of The Johns Hopkins Hospital, over a seven-week period from December 2008 to January 2009. The team found Legionella growing in 50 percent of cultured water samples from 20 electronic faucets -- compared to 15 percent of water cultures from 20 of the older faucets in the same patient care areas. (Legionella causes Legionnaires' disease, a severe and sometimes deadly form of pneumonia.)
Somewhat surprisingly, this study is far from the first to place the germy blame on hands-free faucets. But Snydor's team believes their research is the first detailed analysis to show how and why the automatic faucets harbor more of the nasty bacteria. Researchers took apart four of the electronic faucets, and swab culture tests showed Legionella and other bacteria on all of the main valves. "All of those different pieces, when we took them apart, grew Legionella," Snydor says. "Manual faucets don’t have these parts."
Also, one reason hospitals and other facilities switched to electronic faucets is that they conserve water, "but decreased water flow may increase the chance that bacteria grows, because you're not flushing them through."
Another theory we'd like to offer: Those automatic faucets never work on the first try! You end up jabbing and poking your dirty hands all over the faucet to try to trigger the stream of water. Couldn't that promote the spread of bacteria? "I think people have hypothesized that," says Snydor. But in this study, "nothing on the outside was cultured."
At Johns Hopkins Hospital, all of the 20 electronic faucets were removed from the patient care areas and replaced with the manual kind, as a result of the study. A hundred more are set to be replaced throughout the hospital, and 1,080 manual faucets will be installed in the new clinical buildings currently being built.
We should note that this research doesn't excuse you from post-bathroom hand-washing. "A person goes to the airport, and goes to the bathroom one time -- that’s really low exposure," Snydor explains. "In hospitals, obviously, people have weakened immune systems -- that’s who we worry more about."