The topic of this final paper is internal and external hydrant networks. The paper will explain how hydrant networks work, what types exist, and how they are used to protect property and people from fire. It will also explain the importance of using the internal and external hydrant network at the very beginning of the fire in order to reduce the devastating effects of the fire to the lowest possible level. The paper will also describe the parts of the external and internal hydrant network, the legal norms that must be observed during its installation. It will be shown in practical examples how it is used independently or together with other elements used for fire protection. It will be explained how important it is to check the correctness of the internal and external hydrant network, and how important it is that it must always be in good condition. Strict adherence to the legal regulations that regulate the obligation to install, design and build the hydrant network greatly contribute to the system functioning to the best possible extent should there be human casualties and major material damage.