Wastewater-based epidemiology (WBE) is the analysis of wastewater to detect pathogen levels or activity for public health awareness or action. Pioneered in the 1940s, WBE underwent a resurgence during the COVID-19 pandemic, providing important information about number of cases, outbreaks, and seasonal impact. With advancements in detection technologies and growing interest in environmental surveillance, WBE is poised to become a standard practice in public health monitoring. Here, we provide an overview of the current state of the art of pathogen WBE, including methods of molecular detection, analysis of wastewater data, real-world applications and programs, public health interventions, and benefits and challenges for the field.