Complexity of electronic faucets provides haven for germs
Johns Hopkins Hospital installed electronic hands-free faucets a couple of years ago both as a water-saving measure and to reduce recontamination on the hands of hospital personnel. However, research conducted at two wards at the hospital examined bacterial growth from 20 manual faucets and 20 electronic faucets, each receiving water from the same source. Cultures obtained from the faucets showed that 50 percent of water cultures grew Legionella spp. compared to 15 percent of water cultures from manual faucets.
The problem with the electronic hands-free faucets, which rely on an infrared sensor to detect the proximity of hands, is that the faucets have a more complex valve system than hand-operated faucets. Relying on a garden-variety water faucet valve to gate the entire flow of water would require much more electrical power than is available to electronic faucets, which typically use battery power to operate the electric eye and valve. Instead, in electronic faucets the sensor signal controls a small valve that uses water pressure to amplify the signal and gate the water on and off. This is a much more mechanically complex valve, and even though the hospital periodically flushes the pipe with chlorine dioxide, the nooks and crannies within the valving system provide safe harbors for bacteria.
The report emphasized that these results don’t mean that you should avoid electronic faucets in airports or your workplace bathroom: While the bacteria levels were beyond the limits allowed for a hospital, they were within spec for general public areas. Exposure to Legionella spp. is dangerous for the chronically ill because it can result in pneumonia for people with compromised immune systems; Levels found at the hospital were within the level that can be tolerated by the general public.
On the other hand (so to speak), do airports and office spaces periodically flush their pipes with chlorine dioxide? Public bathrooms are creepy enough without inspiring a mental image of what’s going on inside their pipes.
This study serves as another illustration of the Law of Unintended Consequences.
[Via the L.A. Times.]