how many psi in a foot
Pure water at 60F has about 27.78 inches of water column (INWC or INWG) per psi or approximately 0.43197 psi/ft. This is from memory; but it should be close. Fresh water: 0.43 psi per foot Sea water: 0.44 psi per foot. So, for each additional 10 feet of depth, figure about 4.3 to 4.4 psi increase in pressure. You can calculate this yourself by using the fact that fresh water weighs about 62.4 pounds per cubic foot (pcf) and sea water weighs about 64 pcf.