Most of us know how to calculate capacity and entire tank weight, but none that I've seen have been able to give us a formula to calculate the hydrostatic or outward pressure exerted on the walls of our tanks. This is of particular interest to those, like myself, who are building big tanks. I've taken the mystery out of the calculation and limited it to the following parameters: lbs. per cubic ft. water * height of tank in feet 62 is approx. lbs. per cubic ft. of water, so use that and it'll be pretty accurate. In example, my tank is 5' tall. Even though it won't be filled to the rim, I use that in my calculation. 62 * 5 = 310 lbs/foot^2 To get the total forward pressure, multiply the length * height * above result: 12 * 5 * 310 = 18600 lbs total pressure on front wall (and back since same dimensions. to do it in meters 203.41 * height in meters (i.e. if your tank is .5 meters tall it would be 203.41 * .5 = 115.20 lbs/foot^2 Use the total forward pressure for feet above and convert to sq. meters for a metric version. I can figure it out for you if anyone needs the metric one, but too busy to do it right now.