On Site Sewage Systems Practice Test

The key idea here is that building performance in this context is driven by demand (the wastewater load) relative to what the system can handle, not by the size of the building alone. Increasing gross area by 10% adds space, but it doesn’t automatically generate more wastewater unless more people are using the space. If occupancy stays the same, the number of occupants contributing wastewater doesn’t rise, so the load on the system remains essentially the same and performance doesn’t change. Only when occupancy increases enough—here, by about 15% or more—does the wastewater load reach a new level that can alter performance. So the statement that nothing changes unless occupancy increases by 15% captures the idea that occupancy-driven demand, not area, governs performance changes.