To determine the pressure of water, you would use Force/Area. With a column of water. For example a 4 inch diameter column of water with 24 pounds of water in it. Equation would be 24/12.56637061. Would equal 1.909 psi. But if at the bottom of the column there was a 1 inch diameter tube. Would you take 24 pounds and divide it by the area of 1 inch-(0.785398163 cubic inches) to get the pressure leaving the tube. If that were true would the pressure be 30.55774909psi? It just doesn't seem right. Can someone help me with this?