This paper is the result of hydrogeological survey engineering.

Objective The Beijing−Tianjin−Hebei Plain faces a serious shortage of water resources, and the contradiction between supply and demand is very prominent. Increasing the use of unconventional water resources and forming a diversified water supply pattern is of great significance to effectively alleviate the contradiction between supply and demand and support the socio−economic development and ecological civilization construction of the Beijing Tianjin Hebei Urban Agglomeration.

Methods This paper systematically carries out classified data statistics on supply directions, development and utilization models, and water supply scaleof unconventional water resources. We analyze their development and utilization prospects and ecological environment effects according to the planning and allocation objectives of unconventional water resources in Beijing−Tianjin−Hebei Plain.

Results Unconventional water resources in the area include brackish water, recycled water, desalinated seawater, rain water. The brackish water is mainly distributed in Tianjin, Cangzhou, Hengshui in the central and eastern plains, with a water supply prospect of 5.43×10⁸ m³; Recycled water is mainly used in large industrial cities such as Beijing and Tianjin, with a water supply prospect of 34.22 ×10⁸ m³; Desalinated seawater is mainly used in Tianjin and other coastal cities, with a water supply prospect of 4.19 ×10⁸ m³; The use of rainwater is relatively scattered.

Conclusions (1) There is a risk of soil salinization when brackish water is used for agricultural irrigation, and water and salt regulation should be strengthened. (2) The recycled water is used for ecological replenishment of rivers, the surface water is eutrophic and the groundwater is not obviously polluted; Irrigation with recycled water in shallow groundwater buried areas will increase the risk of nitrate pollution; It is suggested that high-risk emerging pollutants be included in the monitoring system of recycled water use. (3) The concentrated brine and cooling hot water from the tail liquor of seawater desalination may change the distribution, composition and diversity of natural marine ecosystems, which should be paid attention to. (4) The use of rainwater can reduce the water quality risk of sewage entering the river, but excessive use may affect the stability of the regional ecosystem. It is recommended that urban areas appropriately expand the use.