Wastewater treatment is a cornerstone of public health and environmental protection in the United States. As urbanization and industrial activities increase, so does the need for effective sewage treatment. Among the various treatment levels, secondary sewage treatment is the federally mandated minimum for most municipal discharges, designed to remove at least 85% of organic matter and suspended solids from wastewater. But what fraction of Americans benefit from this level of treatment? This article explores the answer, delving into the history, current statistics, treatment processes, and future challenges of secondary sewage treatment in the U.S.