Water network synthesis has focused on maximizing water reuse to minimize freshwater consumption, even though the adverse effect of water use has not been examined until now. This study evaluates and analyzes the positive and negative effects of excessive water reuse on the environmental and economic performance of a water network system. Life cycle assessment and life cycle costing are used to evaluate the environmental impacts and economic costs of the three water systems with the different levels of water reuse. Networking for low water reuse enhances both environmental and economic performance of a water system. However, networking for excessive water reuse deteriorates the economic performance of the water system, even though this networking enhances its environmental performance. Therefore, the positive and negative effects of excessive water reuse should be taken into account in developing new pinch analysis methodologies and mathematical optimization models for water network synthesis.