Which inlets have horizontal openings located in the gutter to admit surface runoff waters to underground conduits?

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

Answer: (C)

Water that runs off the street is collected in the gutter, and the way it enters the underground sewer depends on how the opening is oriented. Gutter inlets are built right in the gutter and have a horizontal opening at the gutter level. That design lets water flowing along the pavement slip directly into the underground conduit through a slot or grate that sits in the gutter. Because the opening is horizontal and located in the gutter, this type is specifically described as admitting surface runoff waters from the gutter into the underground system.

Other inlets are set up differently: curb inlets have openings in the curb face, so water enters through a vertical or edge opening; manhole inlets connect to manhole chambers, not the gutter, and sump inlets collect water at a low point into a sump basin. So the horizontal gutter-level openings point to gutter inlets as the correct choice.