The overall operation problem becomes one of determining which pumps to run and when to run them so that electrical unit costs and electrical demand charges are minimized while at the same time maintaining appropriate water levels in each system tank for normal fire protection and adequate system pressures. A computer model capable of solving the complex operational problem can be developed using two different approaches: a macroscopic or microscopic approach. The macroscopic approach typically employs regression curves to approximate the hydraulics of the distribution system. The network characteristics are in turn provided to the optimization algorithm to generate an optimal operating policy. The microscopic approach to computer control combines optimization algorithms with hydraulic network simulation models and demand forecasting models. Both approaches are discussed in the paper, along with factors to consider in selecting an approach.