Wire to Water Efficiency refers to the the overall efficiency of the pumping system. The pumping system has a prime mover, usually a motor and the pump. The Wire to Water efficiency is calculated as the energy supplied through the wire to the final quantity of water pumped by the system.The Wire to Water Efficiency is obtained by multiplying the efficiency of the motor with the Best Efficiency point of the pump.
Consider a motor which has an efficiency of 95%.
Let us assume that the motor drives a pump which has a Best Efficiency point of .84, then the Wire to Water ratio of the pump will be .95x.84 = .978