Smart Water Network Simulation and Planning System (SWN-SPS) is offered to analyze, plan, and manage Smart Water Network in buildings and infrastructures. The proposed solution will evaluate the transitions of water networks into smart water networks with optimized performance in buildings and infrastructures. Most solutions for water conservation depend on recycling rainwater and some output from sinks to toilets for flashing. This recycling saves water and cost with a rate not more than 25% of the AS-IS model. The proposal has conducted potential scenarios to enhance the water conservation system and make it less costly than other solutions in the literature. It is done with a low rate of capital and running costs. Therefore, an integrated modelling and simulation tool is proposed using Multiphysics modelling to define and evaluate all possible water recycling scenarios.