Method: Hydrostatic pressure is calculated from: P = ρ × g × h where ρ is water density, g is gravitational acceleration and h is vertical water head. For normal water calculations, this gives approximately: 1 m of water head = 9.80665 kPa 10.197 m of water head ≈ 1 bar 2.31 ft of water head ≈ 1 psi The calculation represents static water pressure due to elevation only. Actual pressure in a flowing pipe can also be affected by pumps, friction losses, valves, fittings and changes in velocity.