Wastewater-based epidemiology
Wastewater-based epidemiology (or wastewater-based surveillance or sewage chemical-information mining) analyzes wastewater to determine the consumption of, or exposure to, chemicals or pathogens in a population. This is achieved by measuring chemical or biomarkers in wastewater generated by the people contributing to a sewage treatment plant catchment.
Source: Wikipedia — Wastewater-based epidemiology (CC BY-SA 4.0)