Wastewater and COVID-19 – What are the risks?

by Sara Heger

The current global pandemic caused by COVID-19 has highlighted the interconnectedness of our planet in ways that were underappreciated by the average American until now. In the US, biomedical scientists, physicians, and public health officials are working to effectively respond to the thousands of infected people, while simultaneously monitoring the spread of COVID. In order to accurately assess the damage done by the virus and effectively protect the public, learning more about COVID-19 is critical. Recently published studies demonstrate that COVID-19 affects not only the lungs, but also targets cells along the mucosal layer of the large intestine. To date the CDC has found COVID-19 in the feces of nearly 27% COVID-19 cases.  The amount of virus released from the body (shed) in stool, how long the virus is shed, and whether the virus in stool is infectious are not known.  The risk of transmission of COVID-19 from the feces of an infected person is also unknown. However, the risk is expected to be low, based on data from previous outbreaks of related coronaviruses, such as severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

Recent studies in the Netherlands and Massachusetts have shown that COVID-19 can be detected in wastewater.  Viral particles have been showing up in growing numbers in water treatment facilities since early February 2020. It is important to note that these studies do not distinguish if the virus is dead or alive or if it can cause infection, just the presence and amount of RNA. This research is expanding across the US including at UMN Duluth with the goal of identifying hot spots and detecting early warning signs of future outbreaks.


Back flushing to break up the scum layer creates aerosolization of liquids. This image taken on a humid day shows how much potentially dangerous vapor is released into the air, risking inhalation by ssts maintainers.

Wastewater treatment plant (WWTP) operators and subsurface sewage treatment system (SSTS) maintainers, service providers and installers that clean out septic, holding, and pump tanks along with aerobic treatment units, perform operation and maintenance, and repairs are commonly exposed to untreated wastewater that contains disease-causing organisms including pathogens, which are primarily bacteria and viruses.  The good news is that property owners are not.  WWTP remove all pathogens prior to discharge of the treated effluent from the plant and septic systems are designed to keep all the effluent below the ground, treating pathogens as the effluent travels through the unsaturated soil. 

Here is what we know as of 6/18/20:

  • The World Health Organization WHO has indicated that “there is no evidence to date that COVID-19 virus has been transmitted via sewerage systems, with or without wastewater treatment.” 
  • According to the EPA, COVID-19 has not been detected in drinking water supplies and the current risk to drinking water is low.
  • Wastewater treatment plants and septic systems treat viruses and other pathogens. COVID-19 is a type of virus that is particularly susceptible to disinfection. Standard treatment and disinfectant processes at wastewater treatment plants are expected to be effective.  Septic systems use similar processes along with unsaturated soil to treat pathogens.
  • The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) states there is no evidence to suggest that additional, COVID-19 specific protections are needed for employees in wastewater management operations, and OSHA encourages workers follow routing practices to prevent exposure to wastewater.
  • The Center for Disease Control and Prevention (CDC) notes that wastewater and sewage workers should use standard practices of basic hygiene precautions (e.g. handwashing) and wearing personal protective equipment (PPE) as prescribed for current work task. In consultation with local health officials, onsite sewage system professionals should consider the following routine disease prevention practices for onsite sewage system tank cleaning, operation and maintenance, and repairs to help protect service providers from potential infection of COVID-19.

How to protect yourself and your families

Operators and SSTS professionals are performing essential tasks need to protect public health and safety and must continue to work during this outbreak therefore it is critical that they do it safely.  Wastewater professionals must be provided proper personal protective equipment (PPE), be training on how to use it, and hand washing facilities/waterless sanitizers. Workers should avoid touching their face, mouth, eyes, nose, and open sores and cuts and chewing gum or tobacco while handling sewage.  Workers should wash hands with soap and water immediately after removing PPE or use waterless sanitizers. Do keep in mind that waterless hand sanitizers are not as effective on hands that are dirty with grime and grit therefore it is advisable to use soap and water prior to eating or drinking. 

Property owners should be sure to follow proper hand-washing techniques.  They should confirm that their plumbing is draining properly and if they have a septic system confirm that no wastewater surfacing on their property. 

What about toilet paper and sanitizers?

Toilet paper used in normal amounts will not cause an issue in WWTP or septic systems.  Sanitizer wipes should NEVER be flushed down a toilet (including those labeled flushable). If due to shortages of toilet paper people need to utilize other paper products such as paper towel or Kleenex these items should be placed in the garbage NOT, the toilet.  Property owners should avoid the overuse of sanitizers due to the antibiotic resistant bacteria and the negative impact to septic system bacteria.