Water is one of the most fundamental biological and developmental resources, which in arid and semi-arid countries, including Iran, is strongly influenced by demographic changes, urbanization, consumption patterns, institutional capacity, and the quality of resource management. The relationship between population and water resources is not merely a linear relationship between population size and the volume of available water; rather, it is shaped within a multidimensional context that includes population density, level of urbanization, spatial distribution of population, consumption structure, infrastructural capacity, and managerial responses.

The present study aims to provide a comparative and spatial assessment of wastewater network coverage in relation to population distribution and water stress across the provinces of Iran. The research data were extracted from the Statistical Center of Iran, the Ministry of Energy, the National Water and Wastewater Engineering Company, and relevant scholarly sources, and were analyzed using the Falkenmark Index, the proportion of urban and rural populations covered by wastewater networks, and provincial spatial maps.

The results indicate that although Iran has a relatively favorable status in terms of drinking water coverage, a noticeable managerial gap exists in wastewater network coverage, particularly in provinces experiencing water stress and having considerable urban populations. The comparative findings show that in some arid and water-scarce provinces, despite the greater need for wastewater management and effluent reuse, the level of wastewater network coverage is lower than what would be expected from a policy perspective. Therefore, the development of wastewater networks and water reuse should be considered as part of an integrated water resources management policy, especially in provinces facing severe water stress and high urban populations.