Understand Pool Wall Vulnerability

What happens here

The narrator then elaborates on the structural challenge posed by backfilling an empty pool. He explicitly states, "This is not a retaining wall." This means the pool walls are not designed to independently withstand the significant lateral pressure exerted by external backfill materials such as gravel or stone. If these materials were simply piled against an empty pool shell, the pressure would inevitably cause the pool walls to deform, bow, or potentially collapse inward, leading to catastrophic structural failure.

Goal: Comprehend why an empty pool shell cannot withstand external backfill pressure.