An inverted siphon is a section of a depressed sewer or gravity sewer, which operates under pressure as it is installed lower than the upstream, and the downstream, sections of the pipe. It is a system used to pass under obstacles such as streams or structures.

When inverted siphons to discharge wastewater and/or storm water, they usually cannot be operated entirely free of agglomerations and deposits [Loren2003]. The reverse gradient at the end of the siphon requires a higher velocity than the rest of the line to remain self-cleaning. Since this is not the case, sedimentation often occurs in siphons [DWAA112:2007].