Based on the background of tight total water use control and increasing water demand, water resources have become constraint resources for economic development. In order to implement the rigid constraint system for water resources and promote economical and intensive utilization of water resources, this paper analyzes the current situation of the population and water resources development and utilization based on the available statistics, and combs the water-saving effects and contradictions. On the basis of the carrying capacity of water resources and the principle of ensuring domestic water, the total amounts of domestic water consumption in 2025 and 2030 are calculated as 2.984 billion m3 and 3.329 billion m3. Meanwhile, the paper reasonably formulates the scheme of population development and city planning decided by water constrained by the red line of total water consumption, whose population size in 2025 and 2030 are 45.528 6 million and 45.871 1 million respectively, and whose area of urban construction land in 2025 and 2030 are 3 685.22 km2 and 3 849.54 km2. The results are all within the carrying capacity of water resources.