What is the difference between invert level and reduced level in surverying?

In surveying, the invert level refers to the elevation of the bottom of a drainage or sewer pipe, indicating the lowest point where water can flow. In contrast, the reduced level (RL) is a reference elevation used to simplify measurements, typically expressed relative to a benchmark or datum point. While the invert level is specific to drainage systems, the reduced level can apply to various points on a site for overall topographical analysis. Both are crucial for ensuring proper drainage and site grading.