by Joe Evans, Ph.D.
December 27, 2011

Energy consumption for a given volume of pumped fluid can be a bit perplexing. It has nothing to do with the flow rate of the pump. It involves the wire to water efficiency and head required. An increased flow rate will increase the horsepower required, but horsepower is an indication of the work performed per unit of time. A higher flow rate does more work in a shorter period of time. For example, if a 500 gallon-per-minute pump and a 1,000-gallon-per-minute pump have the same wire to water efficiency and are pumping against the same head, the energy required to pump 1,000 gallons will be the same. If the head is increased or the efficiency is lowered, its energy consumption per given volume will increase.