Water supply management is very important in social development, ecosystem sustainability, and environmental management. For this purpose, this study presents a planning for city water supply management based on water security indicators in Rasht city in Guilan province to formulate and implement a water security policy using mathematical modeling. In this article, a dual-purpose model is used to manage water supply that can minimize the cost of water supply, water shortage and waste. Also, in the proposed model, the amount of water consumption in the urban area is considered uncertain according to the fuzzy approach. According to the results, evaluating the accuracy and validity of the model presented in the water supply system from different water resources shows that increasing the treatment capacity and water resources in the Guilan province can affect the treatment cost and reduce the shortage and wastewater. Regarding the parameters that have a positive effect on the amount of input water, it is required to consider appropriate systems to control the input water and manage such valuable resources. Eventually, forecasting the amount of shortage in the studied area during the next 100 years indicates a linear trend that the amount of shortage increases in an upward manner in each period due to the increased population and decreased amount of precipitation.