Because of rapid urban growth, local water shortages have become a major issue in worldwide. This rapid growth has resulted in limited access to high-quality water sources for many areas, especially in arid and semi-arid regions. Developing additional high-quality sources is not available all the time since such sources are usually remotely located thus costly and sometimes conflict with other areas for water rights. The only remaining and a well-proven conservation source to meet increasing demand is the reclamation of wastewater for non-potable usages. A few studies have been completed for design of reclaimed water distribution through a parallel pipe system - so called potable and non-potable dual pipe system. In previous research, however, attention has mainly focused on the minimization of economic cost and little effort has been contributed for investigating the impact ofWDS construction and operation on the environment. This study includes minimization of greenhouse gas (GHG) production as one of the objectives to incorporate environmental objective. In addition, since the two parallel networks may serve as backup system for each other, system's reliability/availability against mechanical failure (e.g., pipe breaks) is investigated and compared to that of single potable system. Therefore, an optimal design of dual water distribution system is formulated as a multi-objective optimization approach in terms of triple-bottom-line (TBL). This study pursues to provide idea of which systems are more economical, eco-friendly, and reliable in variety of conditions using a simple hypothetical network. The resulting problems are mixed integer problems solved using the genetic algorithm (GA) linked with EPANET.