What is the water table?

The water table refers to the upper surface of the zone of saturation in the ground, which is the depth below which soil or rock is completely saturated with water. When the soil reaches this level, it can no longer hold any more water, and the pores in the soil or rock are filled with water. Understanding the water table is crucial for septic system installation, as it influences drainage and the design of the system to ensure proper wastewater treatment.

Other options describe different water-related concepts. For instance, the idea of soil being free of water relates to the unsaturated zone above the water table, while the surface area of all water bodies addresses geographic features rather than groundwater. The boundary between fresh and saltwater pertains specifically to coastal ecology, not to the groundwater table itself.