Water flows in soil due to difference in the total head. When we estimate pore water pressure, we need to know the pressure head in soil. This video explains how to estimate each head using a simple example 0:18 where water flows in the soil specimen fixed in a tube. Estimations of elevation head 2:15, pressure head 3:21, total head 3:37. This should help you better understand the difference between the heads and prepare you for solving more complex problems, which can be found in the following videos: How to Calculate Pore Water Pressure using Flow Nets    • How to Calculate Pore Water Pressure ...   How to Obtain Hydraulic Gradient and Velocity of Water flow using FLOW Nets    • How to Obtain Hydraulic Gradient and ...