Energy and water are interlinking each other, especially in the water treatment systems. Energy is mainly used to operatethe water treatment plant and to improve the water quality, including water transferring, water pumping, chemical feeding,clarifying, and filtering. The significant challenges of the waterworks authorities are how to produce efficiently and economicallywater supply and how to manage the limited resources like water and energy resources. The Water-Energy Nexus (WEN) is an integratedconcept that considers both energy and water resources in a holistic perspective, so that it can manage the challenges in the optimalway. However, there are some research gaps in the literature. The existing body of knowledge cannot apply to study and analyze the WENin a water treatment plant.... This study aims to study and propose the WEN framework that can improve the performance of the water treatmentsystem. The conceptual model of WEN in water treatment system can be evaluated in terms of the energy and economic performances. Thedeveloped WEN framework in this paper will be applied to a case study in Bangkok, Thailand for performance evaluation under different scenarios.