What is a 1 in 80 fall mean on drainage pipe?

A 1 in 80 fall on a drainage pipe means that for every 80 units of horizontal distance, the pipe slopes downward by 1 unit. This slope is essential for ensuring proper drainage and flow of wastewater, allowing gravity to facilitate the movement of liquids through the system. A steeper slope may lead to faster flow but can also cause erosion, while a gentler slope may risk blockages.