By Peter S. Cartwright, PE

There’s so much we don’t know about the virus behind this pandemic, but we are learning a little more each day. To the microbiologists, this virus is known as SARS-CoV-2, closely related to SARS-CoV-1, the virus that caused the SARS outbreak in 2002-3. Most of the current scientific information and recommendations are based on what we learned in dealing with the SARS virus, but there are significant differences. The normal incubation period is two to 14 days after infection; however, during this time, these people may be contagious without even knowing they are infected.

What are its effects?
In addition to the well-known symptoms of fever, coughing and loss of breath, the CDC has recently added chills, muscle pain, headache, sore throat and loss of taste and/or smell. Additionally, medical personnel are now reporting blood clots and issues with kidneys, heart, intestines, liver and the brain. Doctors also suspect a link between COVID-19 and a rare inflammatory condition, Kawasaki Disease.

So where did this particular virus come from? Virologists estimate that about 1.7 million viruses are lurking on this planet, 75 percent of which are in wildlife. Many of the dangerous ones (SARS, MERS, Ebola, rabies, etc.) have been identified in bats and are readily transmitted to humans, possibly through another vector such as snakes. There is lack of agreement on the specific source of this one.

Is it waterborne?
COVID-19 is spread through respiration from the lungs. Diseases such as salmonellosis and cryptosporidiosis result from eating or drinking but the experts do not feel that COVID-19 can be spread that way. In other words, we catch this disease from inhaling, not from eating or drinking. The World Health Organization (WHO) issued a March 19 Interim Guidance wherein they state: ”Although persistence in drinking water is possible, there is no evidence from surrogate human coronaviruses that they are present in surface or groundwater sources or transmitted through contaminated drinking water. The COVID-19 virus is an enveloped virus, with a fragile outer membrane. Generally, enveloped viruses are less stable in the environment and are more susceptible to oxidants, such as chlorine.”

The virtually ubiquitous practice of chlorinating municipal drinking-water supplies in the US has reinforced the conclusion that this virus will not survive in drinking water. This document goes on to state: “Heat, high or low pH, sunlight, and common disinfectants (such as chlorine) all facilitate die off.” In centralized water treatment applications, WHO specifies a free-chlorine concentration of equal or greater than 0.5 mg/L, at least 30 minutes contact time and pH < 8.0. For non-centralized applications, in addition to chemical treatment (0.5 percent sodium hypochlorite or equivalent disinfectant), they recommend “…boiling or using high-performing ultrafiltration or nanomembrane filters, solar irradiation and, in non-turbid waters, UV irradiation.” Based on this, POU RO technology should be effective. All of these assume careful, hygienic handling practice.

This WHO document also states: “There is no evidence that the COVID-19 virus has been transmitted via sewerage systems with or without wastewater treatment.” As with other pathogenic viruses, it may be present in sewage, but does not appear to present a greater operational hazard to wastewater plant workers wearing the necessary protective equipment.

So how is it spread?
The bad news is that the COVID-19 virus appears to be transmitted through the air in tiny droplets, typically larger than 5µ. Although the virus itself is extremely small, measuring about 0.1µ, it is readily carried in respiratory droplets. When someone coughs or sneezes, huge quantities of droplets are released. What may not be so obvious is that we spray droplets even by talking (also breathing?). These droplets may be suspended for a long time (hours?) and travel significant distances by air movement. The six-foot rule is just an educated guess and some experts feel it should be much farther, perhaps up to 12 feet.

This underscores the value of face masks. It is suggested that N95 masks be reserved for medical and other personnel in direct contact with infected people. This is good advice, as these masks are manufactured to ensure filtration of at least 95 percent of particles as small as 0.3 microns. The good news is that most droplets containing the virus are much larger than this and, depending on the particular face-mask construction, should be effective at removing these droplets. Even home-made masks constructed from old T-shirts or other cloth will help prevent the wearer from infecting people nearby.

The second pathway of COVID-19 exposure is from surfaces. Experts estimate that the virus is infectious for as much as three hours in droplets, four hours on copper surfaces, 24 hours on cardboard and three days on plastic or stainless steel. Note the antimicrobial credit given to copper, which also includes brass. It also appears to be able to survive on the soles of shoes for up to five days. The SARS-CoV-2 virus will not survive for any length of time outdoors, thanks to the excellent disinfecting properties of UV radiation from sunlight. It appears that UV radiation in the 200 to 222-nm wavelength will effectively inactivate (kill) the virus without harm to human skin. It is also readily inactivated by wiping surfaces with bleach solutions (four teaspoons per one quart of water).

The virus can readily enter the body through mucous membranes around the eyes, nose and throat. It is critically important that we keep the virus particles off our hands (which is why we are inundated with advice regarding hand-washing) and to avoid touching your face. If you think of this virus as sitting on everything you touch, that should be motivation to constantly wash. The experts tell us that the optimum procedure is with soap and water (for 20 seconds) and that hand sanitizer (minimum alcohol concentration of 60 percent) should be used only if soap and water are not available.

Facts and fallacies
As with anything so dominant in the news and on social media today, there is a plethora of misinformation circulating. The list below presents some of these along with the truth as provided by respectable authorities.

  • The virus that causes COVID-19 is more deadly than any other pathogen. The data so far indicate the fatality rate at one to three percent; SARS was 11 percent and MERS was 34 percent.
  • Getting COVID-19 is a death sentence. 80 percent of those infected have mild symptoms and get well.
  • This disease is less deadly than the flu. COVID-19 appears to be more deadly than the seasonal flu.
  • The virus that causes COVID-19 is the most infectious pathogen. Pathogens that cause measles, polio, diphtheria and whooping cough are more contagious.
  • Pneumonia and flu vaccinations will protect you from COVID-19. No, they won’t.
  • Antibiotics will work. These are only for bacterial infections and will not work on viruses.
  • Sipping water every 15 minutes will prevent infection. Absolutely will not work.
  • Taking garlic, ibuprofen, echinacea, vitamin C, zinc, elderberry juice, green tea, steroids and other home remedies. There is no evidence that any of these will prevent infection or lessen the symptoms.
  • Hand dryers will kill this virus. No.
  • Either cold or hot weather will kill it. No evidence to support this.
  • Hot baths will prevent infection. No.
  • It can be transmitted through mosquito bites. No evidence to support this.
  • If you cannot hold your breath for 10 seconds without coughing, you have COVID-19. This is not true.
  • Wash your hands with antibacterial soap. While hand washing with soap is absolutely the best way to remove the virus from your skin, the antibacterial ingredient is considered ineffective and is actually a significant pollutant in water supplies.

And the future?
Unfortunately, without much more testing, it will be virtually impossible for the experts to gain the critical knowledge necessary to trace this pandemic and make informed decisions about when and how we can return to some semblance of normalcy. Will recovered patients be immune to reinfection? For how long? Will blood plasma containing antibodies from these people help those with COVID-19 disease recover more quickly? When flu season comes this fall, will COVID-19 come back with a vengeance? Unanswered questions.

At the time of this writing, there is an antiviral drug, Remdesivir, which has shown promise in small studies and has been approved for treatment in hospital settings. Another one, Leronlimab also appears promising in limited trials. Meanwhile, there are at least 70 drugs under development globally, including vaccines from Oxford University and China, as well as those under development by Bointech/Pfizer and Moderna. In the meantime, we owe it to ourselves and loved ones to maintain a healthy lifestyle and outlook, both physically and mentally. The byword today is stay safe—we will get through this if we all work together!

About the author
Peter Cartwright entered the water purification and wastewater treatment industry in 1974 and has had his own consulting engineering firm since 1980. He has a degree in chemical engineering from the University of Minnesota and is a registered Professional Engineer in that state. Cartwright has provided consulting services to more than 250 clients globally. He has authored over 300 articles, written several book chapters, presented over 300 lectures in conferences around the world and is the recipient of several patents. Cartwright also provides extensive expert witness testimony and technology training courses. He is on numerous editorial advisory boards and technical review committees of several trade publications and a frequent lecturer in numerous technical conferences globally. Cartwright is a recipient of both the Award of Merit and Lifetime Member Award from the Water Quality Association and is the Technical Consultant for the Canadian Water Quality Association. He was the 2016 McEllhiney Distinguished lecturer for the National Ground Water Research and Educational Foundation and gave over 35 lectures throughout the world on groundwater contaminant mitigation. Cartwright can be reached via email, [email protected] or visit his website,


Comments are closed.