Glossary of terms

Invert level

The invert level is the elevation of the lowest inside surface of a pipe or channel at a given point, given in metres relative to the adopted vertical datum. In a longitudinal profile the line of invert levels forms the characteristic falling course of the sewer, and the difference between inverts at the ends of a section divided by its length gives the slope. You read the invert at every node — manholes, bends and drop structures. When checking a profile, confirm the outgoing invert is not higher than the incoming invert in the same manhole and that inverts fall in the direction of flow.