Water has always been an undeniable necessity for social and economic development and the survival of vital ecosystems on Earth. The limitation of water resources and varying precipitation patterns indicate that existing surface and groundwater resources must be well identified and studied, and proper utilization should be carried out through precise planning. Water is one of the most important factors affecting any type of density. Therefore, in this research, District Four of Tabriz metropolitan area, as one of the most populous urban areas of Tabriz, was examined to estimate the carrying capacity of water resources. The present study is descriptive-analytical based on a case study. Research data were collected through documentary methods and referencing relevant institutions, including the municipality and the regional water and wastewater company. After integrating and consolidating the obtained information and preparing information layers in the GIS software, relevant maps were prepared. Based on the obtained information, it was revealed that the minimum and maximum population capacity of District 4 of Tabriz, based on the water index and the limiting factor of wastewater production and treatment, equals 172,800and 227,368 people, respectively. Given the population size of the area and a maximum allowable density of 95 persons, it can accommodate a gross density of 229 persons and a net residential density of 195 persons per hectare. However, based on the obtained results, the net residential density of District 4 is 329 persons per hectare, which exceeds the permissible threshold and falls within the critical-pressure range.