Available pressure and volume considerations are important for planning: which statement is true?

• A. Pressure and flow are independent of pipe diameter.
• B. System design must match available pressure and volume to emitters and zones.
• C. Higher supply pressure always reduces system efficiency.
• D. Water can be distributed without regard to pressure differences.

Answer: (B)

The main idea is that an irrigation plan must be built around the actual pressure and available flow from the water supply. When you know how much pressure you have and how much water (volume) you can deliver, you size and arrange emitters, valves, pipes, and zones to match that capability. If the supply isn’t capable of delivering the needed pressure and flow, some zones won’t cover properly or emitters won’t run at their rated flow. That’s why the true statement is that system design must align available pressure and volume with the needs of emitters and zones.

A few quick notes to see why others don’t fit: pressure and flow aren’t independent of pipe diameter—pipe size affects friction losses and thus the pressure available at emitters. Water can’t be distributed without regard to pressure differences—the flow in any part of the system is driven by pressure differences. And higher supply pressure doesn’t always improve efficiency; it can waste energy and create other issues unless managed with regulators or appropriate design.