People who are infected with COVID-19 shed pieces of the virus in their feces, making wastewater monitoring a powerful COVID-19 detection strategy.
Some municipalities use wastewater testing to monitor the progress of the pandemic at the level of neighborhoods or cities, but the technique can also be used to check for COVID-19 infected people in buildings or clusters of buildings, such as schools or child care centers.
How does it work?
A wastewater autosampling robot (an autosampler) is installed with access a facility’s wastewater through a manhole or sewer cleanout. The installation process typically requires a plumber or facilities manager and a technician with experience in environmental engineering and infection control.
The autosampler robot
The autosampler is programmed to collect wastewater approximately every 15 minutes while school is in session (usually 7am – 3pm). A courier service staffed by personnel with safety and infection control training, as well as with training to maintain proper operation of the robot, picks up and logs the jar of wastewater each afternoon. The samples are delivered to a lab that prepares the samples using specialized techniques and analyzes the samples for the presence of COVID-19 using polymerase chain reaction (PCR). Ideally the analysis is completed within 24 hours. The lab then reports whether the samples are negative or positive and the level of positivity (Cq value) to the site or to the SASEA coordinator. For a more detailed step-by-step process, click HERE.
- A closed sewage system (separate from stormwater) that only captures wastewater samples from the target site. For more information on site criteria click HERE.
- Access to the wastewater flow at a manhole or sewer cleanout, ideally at a location after the facility’s wastewater is concentrated prior to going into the municipal sewer system.
- Wastewater autosampling robot. For more information about these devices, click HERE.
- Courier service with environmental engineering skills.
- Lab that can provide daily analysis of the wastewater samples. This analysis requires specialized extraction techniques.
- Coordinator – primary point of contact for the courier service and the lab on behalf of the site(s).
- The presence of COVID-19 on campus may not be detected if infected people do not defecate at their schools or workplaces. COVID infected infants and toddler who wear diapers, for example, will not be detected through wastewater sampling.
- Wastewater sampling can only identify that at least one COVID-infected person was somewhere on site (and used the bathroom to defecate). It cannot show where on a campus the infected individual(s) may have been, or who is shedding the virus.
- Infected people shed virus in their stool very early in their infection (potentially before they might test positive with a nasal swab PCR diagnostic test), and they also sometimes continue to shed virus in their stool after they have recovered and are no longer infectious.
- Some facilities do not have workable access to the wastewater. The wastewater may connect with municipal sewer lines at multiple locations rather than collecting to connect at one location. The appropriate access point may have too many sharp turns to allow for successful extraction, or it may be too deep or steep. Or, the only access point may also collect wastewater from nearby homes or from unrelated facilities.
- Autosampler robot and spare parts (~$3000)
- Environmental engineering courier service
- Lab analysis
- Video explaining the Safer at School Early Alert program to student
- Make the Invisible Visible: Safer at School Early Alert (SASEA)