For the past three decades, a number of studies have been dedicated to water distribution system (WDS) optimal design. However, two key points are often missed or ignored; first, the application systems were often limited to large water supply systems or main transmission lines and function of local distribution lines were ignored; and second, solving real scale systems is lacking mainly due to overwhelming size and computational burden. Here we propose logical and efficient approaches to optimize real-life scale WDS including local distribution lines without excessive computational costs. The optimization results from the proposed methods are compared with traditional methods in terms of system layout, costs (economic and environmental), system reliability, and system performances. It is expected that the approaches presented in this study will be useful for practical implementation of existing optimization algorithms to solve real-life complex system optimization problem.