How does elevation affect required discharge pressure when pumping to a higher level?

• A. Elevation has no effect on the required discharge pressure.
• B. Elevation reduces the required PDP.
• C. Elevation increases friction losses in the system.
• D. Elevation raises PDP by the amount of head required to lift the water (e.g., 1 ft ≈ 0.434 psi).

Answer: (D)

When pumping to a higher level, you must overcome the gravitational head created by that elevation. The pump has to generate enough discharge pressure to lift the water up to the new height in addition to covering any friction losses along the way. The extra pressure needed equals the head required to raise the water, i.e., the elevation difference converted to pressure. In practical terms, about 0.433 psi is added for each foot of lift (since 1 ft of water ≈ 0.433 psi). So lifting water higher increases the required discharge pressure by roughly that amount per foot. Friction losses depend on flow and piping characteristics and aren’t the reason elevation changes the discharge pressure, which is why the key effect of elevation is the added static head from lifting the water.