Philadelphia dumps 12.7 billion gallons of raw sewage into its rivers every year because its sewer system combines stormwater and waste

Philadelphia's sewer system — like those in roughly 700 other U.S. municipalities — combines stormwater runoff and human sewage into the same pipes. When it rains more than moderately, the combined volume overwhelms treatment plant capacity, and raw sewage mixed with stormwater is discharged directly into the Delaware and Schuylkill rivers. According to a 2024 PennEnvironment Research & Policy Center report, Philadelphia's waterways received an average of 12.7 billion gallons of combined sewer overflows per year from fiscal years 2016 to 2024. A single overflow point (T14) discharged nearly 2 billion gallons of raw sewage between July 2023 and June 2024 alone. The city's sewers overflow into local waterways an average of 65 or more days per year. This is not an abstract environmental statistic. It means Philadelphia's rivers — used for recreation, fishing, and as drinking water sources — are potentially too polluted for human contact for up to 195 days per year. Residents in neighborhoods near overflow points experience sewage backups into their basements during heavy rains. The health risks include exposure to E. coli, hepatitis A, giardia, and other waterborne pathogens. Property values near overflow-affected waterways are depressed. The city has spent billions on its 'Green City, Clean Waters' plan to reduce overflows through green infrastructure (rain gardens, permeable pavement), but even at full implementation, CSOs will not be eliminated — only reduced by 85%. The problem persists because rebuilding a combined sewer system into separate storm and sanitary systems is astronomically expensive — estimated at $10-20 billion for Philadelphia alone — and would require tearing up nearly every street in the city. The infrastructure was designed in the 19th century when the engineering assumption was that dilution solved pollution. Federal Clean Water Act enforcement has been inconsistent, and the EPA's own 2004 estimate of 850 billion gallons of annual CSO discharges nationwide has not been updated in two decades, meaning regulators are operating with outdated data. Climate change is making the problem worse: heavier, more frequent rainstorms trigger more overflows from systems already at capacity.