How does the flow elevation change in a gravity system as you move away from the stub out?

In a gravity-based sewage system, the flow elevation typically decreases as you move away from the stub out. This is due to the nature of gravity systems, which rely on gravity to move sewage from one point to another. As sewage travels through the pipes, it generally moves downward to take advantage of gravitational pull, leading to a decrease in the flow elevation as it progresses through the system.

The design of these systems ensures that there is a slope in the pipe, allowing waste to flow downhill effectively. The further the sewage moves from the source (stub out), the lower the elevation will be, assuming there are no pumps or other systems involved to artificially raise or lower the flow. This consistent decrease in elevation is important for maintaining appropriate flow rates and preventing blockages, ensuring that the system operates efficiently.

Therefore, the correct answer emphasizes the fundamental principle of gravity flow in sewage systems.