The article presents the results of a botanical analysis of water systems in the south of Kazakhstan. Hydromacrophytic vegetation of the reservoir reflects its hydrological and thermal regime and can characterize the features of its chemical composition, trophic status, age (as a stage of development). In some cases, phytocenosis and some types of macrophytes can be used as bioindicators, for example, in clean water, as well as to determine the degree and nature of anthropogenic impacts. Metals, metal compounds and toxins cause disturbances in many metabolic processes in plants. As a result, the highly toxic nature of their ions selectively affects the species composition of the phytocenosis. In Shymkent, almost a unique system of treatment facilities has been operating for about 20 years, during this time, resistant species adapted to the environment were selected, and a plant cenosis consisting of dominant species was formed. In this regard, a floristic study was carried out in the canals around the treatment plant, adapted to climatic conditions and pollutants. As a result of the study, the species composition and the number of plant communities decreased due to the toxic concentration of water. It is clearly seen that Cerathophyllum demersum, Lemna minor, L. trisulca, Phragmites australis, Scirpus lacustris, Epilobium adnatum were identified as effective phytomeliorants, significantly reducing the content of the main pollutants in urban wastewater. In addition, algae have been found to be indicators of pollution. Highly effective organic fertilizers can be obtained from the used vascular plants and algae. In general, these data showed that the optimal consortium of wastewater treatment plants at low temperatures should be formed from different ecological groups of plants: coastal, floating and inhabiting the aquatic environment. In addition, among these plants were found sedimentary hornbeam, campfire fish, southern reed, lake reed and a related cypress.