Optimal scheduling of pumps operation in fluid distribution networks (e.g., oil or water) is an important optimization problem. This is due to the fact that the dollar cost and also global carbon footprints of such a major transportation are in mega scales. For example, one of our industrial partners, a Canadian oil pipeline operator, spent more than $18.11 million dollars in 2008 for pumping costs. According to our calculations, this would lead to up to 182,460 tons of CO 2 emissions annually. Therefore, even slight improvements in operation of a pipeline system can lead to considerable savings in costs and also reducing carbon footprints emitted to the environment (by introducing air pollutions needed to generate those huge amounts of electricity). In this paper, a methodology for determining optimal pump operation schedule for a fluid distribution pipeline system with multi-tariff electricity supply is presented. The optimization problem at hand is a complex task as it includes the extended period hydraulic model represented by algebraic equations as well as mixed-integer decision variables. Obtaining a strictly optimal solution involves excessive computational effort; however, a near optimal solution can be found at significantly reduced effort using heuristic simplifications. The problem is efficiently formulated in this paper based on Mixed-Integer Linear Programming. The proposed model is evaluated on a typical oil pipeline network. The numerical results indicate the effectiveness and computationally efficient performance of the proposed formulation.Power charged by second rate for pump j at time t Incidence i,j The (i, j ) entry of the network incidence matrix Lim t j Power limit that the rate of electricity is changed for pump j at time t LP t j Power charged by the first rate for pump j at time t Op t Binary variable which is equal to zero in case the system is shut down at time t and one otherwise P t j Power consumed by pump j at time t P Max j The power that pump j consumes to add the maximum possible head to a fluid with maximum flow rate PH t j Head added to the network by pump j at time t PL t j Pressure loss of segment j at time t Q t j Average flow rate associated with pipeline segment j at time t Q * j The flow rate associated with the maximum efficiency of pump j Q j The flow rate associated with zero efficiency point for pump j Q Max j Maximum acceptable flow rate of segment j Q min j Minimum acceptable flow rate of segment j QSink t i Discharge flow rate from node i at time t QSource t i Flow rate of fluid incoming to node i at time t S t j