The quality of the soil that enables water (or fluids or plant roots) to move downward through the profile. Permeability is measured as the distance per unit time that water moves downward through the saturated soil. Terms describing permeability are: very slow: <0.15 cm/hr, slow: 0.15-0.5 cm/hr, moderately slow: 0.15-1.5 cm/hr, moderate: 1.5-5 cm/hr, moderately rapid: 5-15 cm/hr, rapid: 15-50 cm/hr, rapid: > 50 cm/hr.