Water distribution systems play an important role in supplying water to consumers in a timely and efficient manner. The importance of such systems, in addition to the complexity of their design, has led to extensive research in the area of optimal design of water distribution networks. Traditionally, only system costs are considered in design with few models incorporating environmental impacts. This paper presents a model for designing sustainable Greenfield water distribution networks with the objectives of minimizing life cycle costs, life cycle CO 2 emissions, while ensuring hydraulic reliability for the life time of the system. The model integrates a multi-objective genetic algorithm with water network simulation software, EPANET, using Visual Basic for Applications (VBA). A traditional benchmark water distribution network is used to demonstrate the model. Six scenarios have been developed to test and validate the model for a variety of objectives with different constraints. Trade-offs between life cycle costs and life cycle emissions, along with hydraulic reliability of the system are illustrated. The result of this research is a model that can be used to design large, sustainable and reliable water distribution networks.