Which inlet has a vertical opening to admit surface runoff into underground conduits?

• A. Curb inlets
• B. Manhole inlets
• C. Gutter inlets
• D. Roof inlets

Answer: (A)

Capturing street runoff with a direct vertical drop into the underground conduit is what curb inlets are designed to do. Placed at the edge of the road, they present a vertical opening at the curb line that lets surface water from the street fall down into the storm sewer below. This vertical entry is key for quickly moving runoff from the surface into the underground system while the grate at the curb catches debris and prevents it from entering the pipes.

Gutter inlets are set into the gutter and collect water along the gutter flow, not through a vertical drop at the curb edge. Manhole inlets are broader access points to the sewer system and aren’t defined by a curb-edge vertical opening for surface runoff. Roof inlets collect water from roofs, not street surface runoff.