What is the function of a storm sewer?

The primary function of a storm sewer is to discharge rainwater efficiently from urban and developed areas, thereby preventing flooding and managing stormwater runoff. Storm sewers are designed to collect surface runoff from rain events and transport this water to treatment facilities or directly to water bodies. In doing so, storm sewers help mitigate the risks associated with sudden and excessive rainfall, such as local flooding and erosion.

The other elements associated with stormwater management, such as storing excess water, filtering pollutants, or supporting vegetation, often depend on different systems or processes that can work in conjunction with storm sewers, but these are not their primary functions. Stormwater management may incorporate retention basins or biofiltration systems for storage and pollutant removal, and these features contribute to overall water quality improvement and environmental protection. However, discharging rainwater safely and quickly remains central to the storm sewer's role in urban infrastructure.