Storm sewers are required to transport storm water runoff from roofs, parking lots, streets, and highways to a point of discharge. Storm water runoff is the water that accumulates on these surfaces during rainfall or snowmelt events. Without proper drainage systems, this runoff can lead to flooding and damage to infrastructure.

Definition of Storm Sewers:
Storm sewers are a type of infrastructure designed to collect and convey storm water runoff. They are separate from sanitary sewers, which transport domestic and industrial wastewater to treatment facilities. Storm sewers are typically made up of a network of pipes, inlets, and manholes that efficiently move storm water from one location to another.

Importance of Storm Sewers:
Storm sewers play a crucial role in managing storm water runoff and preventing flooding. They are designed to quickly and efficiently transport large volumes of water to a point of discharge, such as a nearby river, lake, or detention pond. By doing so, storm sewers help protect properties, roadways, and other infrastructure from the damaging effects of excess water.

Components of Storm Sewers:
1. Pipes: Storm sewer pipes are typically made of materials such as concrete, corrugated metal, or high-density polyethylene. They are available in various sizes and shapes, including circular, elliptical, and rectangular. The selection of pipe size depends on factors such as the expected flow rate and the area to be drained.

2. Inlets: Inlets are openings in the street or curb that allow storm water to enter the storm sewer system. They are typically equipped with grates or filters to prevent large debris from entering the pipes. Inlets can be found along the edges of streets, parking lots, and other surfaces that generate runoff.

3. Manholes: Manholes are access points that allow maintenance crews to inspect and clean the storm sewer system. They are usually located at strategic intervals along the sewer line and provide a means of entry for personnel and equipment.

4. Outfalls: Outfalls are the points of discharge where storm water is released from the storm sewer system. They can be located in natural bodies of water, detention ponds, or other designated areas. The design and placement of outfalls are important considerations to ensure that the discharged water does not cause erosion or other environmental impacts.