Number of sewer overflows in the U.S. 1985-2024, by state

From 1985 to 2024, at least 8,612 overflows were reported in combined sewer systems in the United States. During this period, Pennsylvania was the state with the highest number of overflows with almost 1,700 events. A combined sewer system collects rainwater, and domestic and industrial wastewater into one pipe, to later be transported to a treatment plant. When the capacity of these systems gets exceeded, untreated runoff flows to nearby waterbodies. In the U.S. combined sewers are mostly located in the Northeast.

自1985年至2024年，美国合流制排水系统中至少发生了8,612次溢流事件。在此期间，宾夕法尼亚州以近1,700起事件成为溢流数量最多的州。合流制排水系统汇集雨水、生活及工业废水于同一管道，随后输送到污水处理厂。当这些系统的容量超限时，未经处理的径流将流入邻近水体。在美国，合流制排水系统主要分布在东北部地区。