Permeability is best defined as?

Permeability is best defined as the rate at which water can flow through soil. This concept is crucial in the context of on-site sewage facilities (OSSF), as it directly influences how wastewater is treated and how effectively it can be absorbed and filtered by the soil. High permeability indicates that water can move through the soil quickly, which is often desirable for drainage and treatment purposes, while low permeability can lead to waterlogging and potential failure of the OSSF system.

The other definitions relate to different aspects of soil properties, such as retention of water, capacity to hold nutrients, or general moisture content. While these are important factors in soil health and performance, permeability specifically addresses the movement of water through the soil matrix, making it integral to the understanding of how on-site sewage systems function. This distinction is critical for engineers and installers working with OSSF systems, as they must evaluate soil permeability to design effective wastewater treatment solutions.