Every gauge you read, every tank you climb, and every pump curve you check is speaking one of two languages: pounds per square inch (psi) or feet of head. Learn to translate fluently between them and half of your operator math problems solve themselves — this guide gives you the one constant that unlocks it all, plus the physical reasoning behind it so you never have to just memorize a number you don't understand.
What Is Pressure?
Pressure is force spread over an area. In water systems we measure it in pounds per square inch (psi) — literally, how many pounds of force are pushing on every square inch of pipe wall, gauge diaphragm, or your hand if you stuck it in front of a hydrant nozzle.
Pressure=AreaForce A pressure gauge on a hydrant, a water main, or a customer's spigot is measuring this directly. Water itself has weight — a cubic foot