Pankivskyi, Y.I. and Oshurkevych-Pankivska, O.Y. (2023). “Water Supply and Sewerage Systems”, In: “Environmental Science, Technology, Engineering, and Mathematics (STEM)”, Wang, L.K., Wang, M.H.S., and Pankivskyi, Y.I. (Series Editors). 261 pages. May 2023. Lenox Institute Press, Auburndale, Massachusetts, USA. https://doi.org/10.17613/x5qn-d460 ………. ABSTRACT: The rational use of water resources has gained global importance today. The issue of complex use of water resources, the industry and agriculture impact on their state, the need of application of the drainless circulating water supply systems on the basis of highly efficient water and waster treatment mrthods have become the main directions of the development of the water technologies and environment engineering. This handbook was developed for education of specialists capable to solve the tasks of protection and rational use of natural resources. Its purpose is to develop an approach to the selection and implementation of methods of engineering solutions to the problems of rational nature management in the field of water usage to meet the water needs of human society in various sectors of the economy. The main aspects of the physics and chemistry of water, the composition and properties of natural waters and wastewaters, the water quality requirements for various purposes, the systematization of water treatment methods, the technological processes implemented in water treatment systems, the water supply and sewerage communications, the wastewater treatment and their sludge treatment, the aspects of rational water usage in various economic sectors have been considered in current work.