What does undisturbed soil between plumbing systems help to ensure?

Undisturbed soil between plumbing systems is crucial for maintaining system integrity and safety. When soil remains undisturbed, it provides a stable supporting structure for pipes and other plumbing components. This stability helps prevent issues such as shifting, settling, or soil erosion that could compromise the piping systems.

Moreover, having undisturbed soil helps in preventing potential damage to the plumbing systems from external pressures or environmental changes. It contributes to a reliable installation, which is essential for ensuring that the plumbing functions correctly over time without leaks or failures that can lead to safety hazards for building occupants.

In contrast, the other options relate to conditions that may not be directly influenced by the condition of the surrounding soil in the same way. For example, while optimal drainage is important, it primarily concerns the flow of water through the system and drainage design rather than the soil's disturbance. Similarly, increased water flow and reduced water pressure relate to system design and operation rather than soil stability.