What is the primary purpose of the lead-lag arrangement of the two potable water pumps supporting a typical potable water system?

Correct Answer: Option A — Enabling the lead pump to cycle on and off during periods of relatively low demand and the lag pump to assist the lead pump only when the demand is high.

Lead-lag arrangements optimize pump runtime and reliability. The lead pump handles normal demand cycles. If demand exceeds the lead pump's capacity, pressure drops further, triggering the lag pump to assist. This ensures adequate pressure during peak usage while preventing unnecessary wear on both units during low demand.