With the freshwater supply being constant, the increase in population and in the amount of water used, as well as desertification caused by climate change, humanity is warned to manage the available water resources responsibly: to satisfy its needs but to avoid wasting resources. All this is included in the idea of sustainability, to which Hungary had committed itself. At the same time, sustainability constitutes a characteristic feature of green library practices aimed at minimizing negative environmental impacts. Water management is not the main area where libraries can reduce their burden on the environment. It is, however, an area in the institution's operation, that offers other possibilities - in addition to eliminating dripping water taps -, to serve environmental awareness and sustainability which is a global challenge today, and to take responsible action. The possibilities include green roof solutions, designing the building's environment to help to save water, as well as creating a rain garden to reduce the nature-damaging effect of contaminated rainfall. The paper presents these possibilities in more detail. [ABSTRACT FROM AUTHOR]