This lecture delves into the properties of water in soil, covering topics such as capillary pressure, hydraulic head, pressure head, and gravitational head. It explores the concept of capillary tension, the use of tensiometers to measure hydraulic charge, and the relationship between suction and water content in unsaturated soil. The lecture also discusses the determination of hydraulic charge in saturated and unsaturated zones, the soil moisture characteristic curve, and the functions describing water retention in soil.