What does the term "combined sewer overflow" (CSO) refer to?

The term "combined sewer overflow" (CSO) specifically refers to a situation where stormwater and wastewater converge in a single pipe system and exceed the capacity of that system, leading to the overflow of untreated or partially treated sewage into the environment. This typically occurs during heavy rainfall or storm events when the volume of water exceeds the drainage capabilities, resulting in the discharge of mixed sewage and stormwater into nearby water bodies, which can pose a significant risk to public health and the environment.

Understanding this concept is essential for managing sewer systems effectively, as CSOs can lead to pollution and require specific mitigation strategies, such as improved drainage infrastructure or increase in capacity through system upgrades. Other options might address related aspects of sewage management, but they do not define the specific situation of combined sewer overflows as accurately as the primary definition provided.