What distinguishes a sanitary sewer system from a stormwater drainage system?

The distinction between a sanitary sewer system and a stormwater drainage system lies primarily in their functions and the types of materials they are designed to transport. A sanitary sewer system is specifically intended to carry wastewater, which includes sewage from residential, commercial, and industrial sources. This is collected and transported to treatment facilities where it is processed before being released back into the environment.

On the other hand, a stormwater drainage system is designed to manage surface runoff, which occurs during rain events or snowmelt. This system is intended to divert rainwater and melted snow away from streets, sidewalks, and other surfaces to prevent flooding and water accumulation. The stormwater is usually not treated to the same extent as wastewater and is often released directly into natural bodies of water or designated drainage areas after flowing through the system.

This understanding clarifies why the correct answer is focused on how sanitary sewers manage wastewater and how stormwater drains are concerned with surface runoff, capturing the key operational differences between these two essential systems.