A comparative study of the regularities of variation in water deficit of tree species (Populus deltoides Mersh, Acer Semenovii Rgl.et Herd, Elaegnus angustifolia L, Salix alba L.) of plant species in monthly and seasonal dynamics when they grow together in conditions of technogenic and insufficient soil moisture supply.The article studies the water-deficient state of four tree species belonging to different ecological groups located in the western part of the city of Ust-Kamenogorsk, adjacent to production sites. The studied plant: Populus deltoides Mersh, Acer Semenovii Rgl.et Herd, Elaegnus angustifolia L, Salix alba L. When water is scarce, it does not lose its turgor properties, the leaves are reduced, and the intensity of transpiration decreases accordingly. The osmotic pressure is very high in xerophytes. The root system intensively pumps out water, but uses it sparingly. In the water balance of the plant-there should be no shortage in the ratio of the amount of water of the plant and the amount of water penetration. The water regime depends on the structure of the soil, as well as on the degree of perception of water in the soil by the plant, which is very closely related to the mechanical structure of the soil. Since most of the factors of the general environment change and affect organisms at different levels each time, during the growing season the plant is formed, adapting to changes in the same environment. The amount of water is at its level, there are no violations of the water balance of the plant. The absence of large fluctuations in the values of air and soil humidity also affects the water regime of the plant.