The goal of this master's thesis was to design a hybrid membrane-based system with a capacity of 5 m3/h to obtain water of equal or better quality than the quality of water for injection achieved by the distillation process. Water for injection is intended for the preparation of drugs for parenteral administration as well as for dissolving and diluting preparations for parenteral administration and is most often obtained by distilling purified water. Based on the recent revisions of the chapters of the European Pharmacopoeia, water for injection can also be obtained using reverse osmosis in combination with other suitable technologies, such as electrodeionization, ion exchange, etc. It is generally known that energy costs in the field of distillation are enormously high, and by applying aforementioned technologies for acquiring water for injection opens up the possibility to reduce carbon footprint while reducing capital and operating costs. In the first part of the thesis, the importance and role of water in the production and manufacture of pharmaceutical products is described, and the requirements set for different types of water in the pharmaceutical industry are listed. Then, numerous technological solutions that can be applied to obtain water of a certain quality are theoretically presented and described. In the second part of the work, the system for the preparation of water for injections was dimensioned. The computer software WAVE (Water Application Value Engine, DuPont) was used for the calculation of ion exchange and reverse osmosis, which was served for modeling and checking the operation of the system, as well as improving the utilization of the process, with a focus on the lowest possible energy consumption. Calculations of other technological processes were also presented in the work, and the necessary equipment was selected from the catalogs of various manufacturers. The P&I diagram of the system as well as the plant layout with the equipment and piping are enclosed.