We’ve all seen those images on TV and in films of doctors lining up at a sink to deep clean their hands, wrists, and arms before performing an operation. The goal is to ensure no pathogens on their hands are transferred to the patient or the medical equipment.
Scrubbing like a surgeon has become synonymous with hand hygiene for people in all professions. However, as careful as they are, they may not be aware that viruses, bacteria, and other germs may still be present on their hands and surprised about the source of these pathogens. A study published in Applied and Environmental Microbiology in March 2017 found that drains—which are dark and moist— are a perfect setting for germs to thrive.
Setting up the study
To conduct the study, scientists assembled a row of sinks typical of what one would see in a hospital setting. The sinks and components (i.e., faucet handles) were sterilized before the test.
As a precaution, Plexiglas shields separated the sinks to prevent contaminants from one sink from invading another. Each sink had its own pipe “p-traps,” installed directly below, and all were connected to the same pipe below the drains. P-traps are installed in all drains in the U.S. to prevent sewer odors from being released into a restroom or wash area.
To test the p-traps, scientists seeded them with harmless, fluorescent bacteria. This allowed the researchers to determine if and where the microbes traveled up the drains. The researchers also supplemented the bacteria with daily additions of a “nutrient broth to mimic liquids commonly poured into hospital sinks.” Then, they followed the hospital’s regular routine to clean the sinks.
Analyzing the research results
The bacteria down in the drains flourished. These pathogens soon began climbing up the drain at 2.5 centimeters (about an inch) daily. As the researchers continued to use the sinks, the bacteria inched their way to the top of the drains. Contaminated water splattered around the base of the sink.
This splatter had the potential to come into contact with the users’ hands, wrists, and arms. The scientists found that even if only one p-trap was contaminated, that was enough for the bacteria to infiltrate three other sinks through the common drainpipe below.
According to the researchers, “transmission of bacteria between sinks via a common pipe was a key finding in this study [because it] highlights the premise that a more continuous system with shared microbiology” can spread to more than one isolated sink.
If cleaning staff in schools, offices, and other commercial facilities wipe sinks using only an all-purpose cleaner, they will likely do little to sanitize or disinfect the sinks. Even if they use a sanitizer or disinfectant to wipe the sink, that may not eliminate the pathogen buildup under the drain cover. In other words, no matter how effectively we clean the sink, it still may spread contamination.
Protecting your health with a clean drain
This study points out that when it comes to protecting human health, cleaning contractors must give sink drains—in fact, all types of drains, including floor drains—more attention. Drain care may be something that has been overlooked, even during the pandemic. But it cannot be ignored any longer.
Cleaning crews in commercial kitchens and in the food surface industry—which has long been aware of the need to keep drainpipes clean—often use a citric-acid-based cleaning solution.
“Commercial kitchens often use citric acid to clean fruits and vegetables [because] it has proven safe and effective,” said Hannah Johannes, marketing director for ProNatural Brands. “As the [citric acid] is used, it washes down the drain, sanitizing the pipes below.”
Another option is to develop what Johannes calls a “drain maintenance program” designed to eliminate pathogens in the drainpipe and remove debris buildup in the pipe below. “Keeping the pipe clean helps prevent blockages from developing,” Johannes said.
To accomplish this, many commercial kitchens use a citric-acid-based disinfectant with an applicator that coats the pipes below with foam. “It is the disinfecting foam that eliminates the pathogens,” Johannes said.
We have learned over the years—especially the last three years—that cleaning for health is a journey. We are always becoming aware of more steps we need to take to keep people healthy. Establishing a drain maintenance program is just one more thing to add to the roadmap in our cleaning for health journey.
