Some germs, like those that cause flu or COVID-19, can be found in the feces of someone who is sick, even if they don't feel sick. When that person goes to the bathroom and flushes the toilet, those germs go down to the sewer and into a wastewater treatment plant. Harris County Public Health (HCPH) collects sewage samples at wastewater treatment plants across the county and tests those samples to figure out what germs are present and how many there are.

This process is known as wastewater-based epidemiology (WBE). WBE is a very helpful tool. When the number of germs goes up, we know that more people are getting sick, and can alert the community. For example, doctors and nurses can prepare to see more sick people and know what illnesses they might see in clinics and hospital. It can also help every day citizens know that more people are getting sick and allow them to take steps to keep them and their loved ones healthy.