What We Flush
Down the Toilet Can Tell Us a Great Deal
We call it “wastewater,” but we don’t want to waste it.
The information it holds about COVID-19, influenza (flu), respiratory syncytial virus (RSV), norovirus, and a growing list of other infectious diseases is invaluable. It can tell us about infection levels and trends across an entire community.
Scientists have used wastewater-based epidemiology for decades. However, research during the COVID-19 pandemic unlocked the potential for wastewater monitoring to track respiratory diseases including SARS-CoV-2, the virus that causes COVID-19.
Researchers at Stanford University developed an innovative testing method using wastewater solids that was put into practice at 10 wastewater treatment plants in November 2020 and evolved into the WastewaterSCAN program. Since then, the program has used its methods to rapidly detect specific COVID-19 variants and a growing list of other diseases such as flu, RSV, norovirus, and mpox.
Simple, Sensitive, Complete
At the height of the pandemic, when clinical testing for SARS-CoV-2 was widespread, our results tracked case counts closely.
Using solids in wastewater, which carry about 1,000 times more viral genetic material than liquid sewage for many viruses, this method can identify a handful of infections per 100,000 people served by a wastewater system from a pea-sized sample.
No one who uses the sewage system is left out, including residents and neighborhoods historically underserved by the healthcare system. Analyzing wastewater does not require people to be tested by healthcare providers or to report home tests. It’s anonymous. Wastewater monitoring does not identify individuals or households.
Results from monitoring of wastewater solids can be directly compared from place to place and over time.
Wastewater treatment plants in participating WastewaterSCAN locations collect and send wastewater samples through overnight mail to our lab partner and have results posted on our data dashboard within 48 hours of arrival.
Quicker turnaround for results can warn public health officials of a coming rise in cases before they show up as clinical results. For COVID-19, an infected person’s waste shows genetic markers of the COVID virus without the person needing to realize that they are ill, seek out a test, or wait for test results.