wisrob, pressure in a liquid can be calculated by multiplying its density by height. The density of water is about 62.25 lb /sq. ft. Multiplied by height, 6 ft., this gives 373.5 lb. /sq. ft. To convert this to lb. /sq. in., divide by 144. The answer is 2.59 lb. /sq. in. and that's my final answer.