Dave Yates: Legionella and COVID-19
The issues surrounding thermal scalding and bacterial amplification.
We just finished unpacking and sterilizing our peapod grocery delivery this morning: Anything going in the house was wiped down with paper towels soaked in Clorox disinfectant. For Lois and me, our self-imposed stay-at-home quarantine began when I returned home from Atlanta on March 6. I have a client in Atlanta, which requires me to fly in monthly from Harrisburg, Pennsylvania or Baltimore airports.
We were aware of COVID-19 prior to my flight on March 1, and I did pack two pocket-sized hand sanitizers for the trip. Everything went well until I arrived in the Atlanta airport for the flight home and was confronted by an exceptionally long security line that wound back and forth — no social distancing possible — for 2.5 hours. When it was finally my turn, the security scanner ate one of my shoes! Fifteen minutes later, it spit out my shoe along with some added attention from TSA wanting to know why my shoe was detained. They had to check with the TSA folks manning the scanner to ensure I hadn’t been trying to smuggle something in the shoe. Good thing I had arrived early!
The tram to the terminal was a sardine can packed with folks crammed in shoulder-to-shoulder, and all sharing germs freely on hand-straps and bars as we all braced for the “warning, tram is stopping (or starting).” Liberal applications of hand sanitizer were applied at every opportunity. The flight home was full with several covidiots sneezing/coughing without any attempt at covering up. I have COPD, which puts me in a higher risk group, and we’re both over 65.
Are killers lurking?
Will COVID-19 be able to spread, as the SARS coronavirus did via compromised plumbing traps as happened in a 50-story apartment building in Hong Kong? At this time (April 13), the CDC doesn’t believe COVID-19 can survive in potable water systems or sewage/gray-water, but we really don’t know this emerging novel coronavirus very well, and no verified treatments or vaccine are currently available.
We do know that HEPA filtration works well for most airborne contaminates and effectively traps particles 0.01-microns or larger, from this NASA study: go.nasa.gov/2RppyrM. And viruses range in size from 0.004- to 0.1-microns, with COVID-19 at approximately 0.125-microns. Given that the COVID-19 virus can be captured in a HEPA filter, and that this virus is primarily a person-to-person transmission with poor survivability in air (said to be three hours if water droplets are aerosolized in a sneeze), it is certainly possible HEPA filtration would have the potential to help. Bear in mind that the HEPA filter is a bypass system that doesn’t treat 100% of passing air.
Ultraviolet light can be quite affective at killing viruses and bacteria, and also reduces odors. A HEPA + ultraviolet sterilization + MERV-8 pleated filter would effectively treat air-based heating/cooling systems and, overall, greatly enhance IAQ. If outdoor air is also introduced by way of an ERV or HRV air-to-air heat exchanger, IAQ is going to be about as good as it gets in a residential application. Conclusion: HEPA + UV + MERV-8 + ERV/HRV works extremely well for contaminates, bacteria and viruses that survive for long periods in air, but not so much for COVID -19.
On the other hand, COVID -19 has been detected in human feces, and flushing a toilet aerosolizes fine water droplets, which can contain COVID -19 and remain airborne for 15-minutes, or longer (exacerbated by the use of exhaust fans), allowing the virus to be inhaled (stalls in public restrooms) or settle on skin, clothing, wood, stainless steel, china, etc. Given the fact that COVID -19 can live for hours or days depending on the surface material, the potential for transmission is real.
The same can be said for your hands becoming contaminated and touching your face. No touching, especially you, men (mouth, eyes, nose)! It’s precisely why we are now washing our hands with soap 4 million times a day. Flushing a toilet can also spread Legionella bacteria and Legionnaire’s disease kills more people in the U.S. than any other reportable waterborne disease.
Legionella, on the other hand, survives and thrives in our potable water systems. The recent COVID -19 induced panic buying of toilet paper has led to a much higher demand for bidet-style toilet seats that incorporate soothing warm water to rinse then blow dry your nether regions. The warm-water reservoir is a virtually perfect bacterial amplifier for Legionella bacteria.
Our water heaters, tankless included, are also known bacterial amplifiers. While tankless water heaters don’t have the same volume as tank-style water heaters, they all come from the factory set for 120° F. I remember when water heaters arrived from the factory set to maintain 140°, and dishwashers did not have a sanitizer rinse because 140° was hot enough to kill the bacteria.
Thermal scalding, and lawsuits, along with claims that 120° was a safe water temperature drove manufacturers to turn down the thermostats and aquastats. Did that eliminate thermal scalding? No. Thermal scalding cases continued unabated. However, that did set up an environment where Legionella can survive and thrive. Other contributing factors are pH that needs to be between 5.5 and 8.0 (majority of our potable water systems); water temperature between 55° and 133°, biofilms (present in all of our potable water piping), and stagnation (when any system is at rest, or unused portions).
Raise it back up to 140°! My home’s hot water is maintained at 140° with a 24/7/365 recirculation loop and the return at my indirect tank is 135°. The total developed length is 150-feet and insulated. At all points of use, there are scald-guard devices to limit hot water to 120°. Energy codes be damned, my family’s safety trumps a circulate only when usage occurs rule.
The same could be applied to known facilities where Legionnaire’s disease deaths often occur, such as hospitals, senior citizen homes and other health care facilities. One school building I recently surveyed has their potable hot water storage tank set to maintain 140° with a mixing station for everything but the kitchen. Water leaves for the student bathrooms at 120°, but is again reduced to 110° via scald-guard mixing valves near the bathroom sinks. They have constant hot water circulation.
Stagnation is now looming large due to the COVID-19 shutdown of non-essential businesses and schools. When we do finally get through this pandemic, it would be tragic if there follows an upsurge in Legionnaire’s disease due to rampant bacterial blooms in all those stagnant potable water systems. Those who fail to adequately flush their potable hot and cold systems will be putting their building occupants at risk.
Biofilms exist in all potable water lines unless something in the water chemistry affects the existing bio-films and strips them away, sending Legionella bacteria along with flow as happened in Flint, Michigan. That led to an upsurge in Legionnaire’s disease and lead poisoning, as many of the water service lines were lead and stripped of the protective biofilm and exposed to the more aggressive water.
Given that Legionella bacteria are ever-present in our environment — including our municipal potable water supply systems — it would make perfect sense to treat incoming cold potable water as is often done in European countries — as I discovered at the ISH trade show in Frankfurt, Germany, while visiting the Water Halle.
Incoming cold water is subjected to ultrasonic bombardment to break up cysts of one-celled host critters exposing Legionella to ultraviolet radiation to sterilize the bacteria and lastly copper-silver ionization, which, unlike chlorine, eradicates Legionella bacteria, penetrates biofilms and has a long-lasting residual affect where intermittent stagnation occurs.
Plumbing codes are slow to change and lobbyists, sadly, hold sway too often where protecting the health of the nation would increase costs of construction. Consumers, for the most part, are blissfully unaware of the issues surrounding thermal scalding and bacterial amplification. If engineers, architects and designers were to specify these changes, there would be a far better chance codes would follow their lead.