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The optimization technique allows for the inclusion of pumping costs. As a result of the computation of the pressure distribution, the flow rates through the pump and the pump head are obtained. This permits the computation of pumping cost if the percentage of time the pump is running at this operating point is specified. It is again possible to specify several load cases, each with its own percentage of time. The program will then calculate and accumulate the pumping cost and add it to the pipe cost.

Pumping energy cost can be divided into lift energy and friction energy. For the purpose of the program, lift energy is the pumping energy required when the largest pipe sizes in each group are used. As smaller pipe sizes are used, energy to overcome friction increases. This extra friction energy is not included in the cost test described earlier because it is not known until the pressures are balanced. The total energy cost is used for final comparisons. In most water systems, the extra friction energy is small compared with other costs. There exists however, a clear trade-off between pipe cost and energy cost. Smaller, less expensive pipe size combinations will require more energy, and therefore higher cost, to overcome friction.