“…The fi nal balance of cost and income over the life-cycle period (Porter et al, 2004) should be the key factor in evaluating the feasibility of a water pipeline-maintenance project. This balance, which is referred to as the value index V 0 , is the resulting value that can be produced by the project operation, and can be expressed as : 23.41] in which B, I, E, C 0 , and C M are the accumulated total amounts of social benefi t, income gain, operational expense, initial cost, and maintenance cost, respectively, during the life of the project.…”