In this study, a design approach which minimizes the construction and operation costs of water distribution line with differential evolution algorithm is proposed. Digital Elevation Model, monthly water demand, technical codes and unit prices of construction items are defined to optimization module in order to realize the cost optimum design. Pump, pipe diameter and type are defined as design variables. Construction cost of the design is computed by the unit price of the cost items. To determine the annual operation costs, flow is computed according to the Darcy-Weisbach equations. Pumping duration is determined and annual energy cost is computed. Net present value of the investment is computed by considering the time value of the money which is evaluated by the debt interest rate. Minimum-cost design alternative is searched by differential evolution algorithm. As a result, the best pump and pipe combination is obtained and summation of the construction and operation costs are minimized. Minimization of the sum of the investment and operation costs may provide the opportunity of significant improvement in the budget of the municipalities in the long run. Consequently, implementation of the proposed design approach will be beneficial for the local authorities.