What does the term "invert" refer to in sewer construction?

The term "invert" in sewer construction specifically refers to the inside bottom surface of a pipe. This point is significant because it relates to the flow of sewage or wastewater within the system. Understanding the invert level is crucial for ensuring proper drainage and determining the slope or gradient of the piping system, which is essential for effective wastewater flow without blockages or backflow. The invert is typically measured at the lowest point inside the pipe, which allows engineers to evaluate how wastewater will travel through the sewer line based on gravity and pipeline design. This concept is foundational in the field of civil engineering and surveying, particularly when designing and analyzing sewer and drainage systems.