At first glance, you'd assume comparing the relative cleanliness of water dispensed from 20 newly installed hands-free faucets equipped with electronic-eye sensors to a similar number of old-school faucets with knobs in the rooms of patients at Johns Hopkins Hospital would be a waste of time. Not so, according to infectious disease experts at Johns Hopkins University School of Medicine.

Those hands-free faucets do save on water, but are a magnet for Legionella bacteria. This strain of bacteria, commonly found in public water systems, causes few problems for healthy folks, but can be very harmful for patients with compromised immune systems -- think auto-immune diseases like HIV/AIDS and chemotherapy treatments.

Scientists found Legionella growing in more than three times as many water samples taken from electronically-controlled water faucets near or in patient rooms than manual ones. Moreover, weekly tests showed half as much bacterial activity in manual faucets, compared to wired faucets.

These logic-defying results shouldn't come as a complete surprise, however, considering traditional hand-drying with paper towels may be the smarter hygienic choice than using hands-free, warm-air hand dryers in public restrooms too.

PhysOrg.com March 31, 2011

Baltimore Sun/Picture of Health March 31, 2011

LiveScience March 31, 2011

NPR/Shots April 1, 2011