An outfall is a sewer that discharges treated sewage effluent to a waterway on land (a land outfall ) or to the ocean (an ocean outfall ). An ocean outfall may extend several miles offshore, discharge to the ocean by nozzles at the end of a spreader or T-structure. Outfalls may be constructed as an outfall tunnel or subsea tunnel and discharge effluent to the ocean via one or more risers with nozzles.

See also Night soil, Greywater