The level below which soil is saturated is called the water table.

Here's a breakdown:

* Water table: The upper surface of the zone of saturation, where groundwater completely fills the pores and spaces in the soil and rock.

* Zone of saturation: The area below the water table where all the spaces in the soil and rock are filled with water.

* Zone of aeration: The area above the water table where the soil and rock contain both air and water.

So, the water table marks the boundary between the saturated zone and the unsaturated zone.