Can anybody help? I am not a physics or science expert. So be patient and laymens terms please. I am trying to calculate the pressure of water on the side walls of a water barrel that I make to store rain water collected from roofs. The barrels have an inside bladder that is clad with wood. Is the pressure greater at the bottom? What is the pressure per square metre. Is there a formula that i can use to the calculate the water pressure according to the height, length and width of my barrel.