Geothermal energy is important for achieving sustainable development in the modern era, with geothermal water currently being the most extensively developed form of geothermal energy. This chapter takes a focused look at the challenges stemming from the development of geothermal water. It provides a concise review of advancements in geothermal water research, covering a range of topics such as geothermal water chemistry, temperature, quality assessment, numerical modeling, as well as its occurrence in karst systems and the Guanzhong Basin in China. The chapter underscores the importance of geothermal water in resolving energy–environment conflicts, emphasizing its benefits as a reliable and sustainable energy source. It also addresses its potential environmental impacts and its pivotal role in maintaining ecological balance. Despite significant progress, geothermal water research remains an ongoing endeavor. This chapter concludes by proposing several research priorities for the future, including the formation mechanisms of geothermal water, biogeochemical processes of trace and minor elements associated with geothermal water, and strategies for the reinjection of geothermal water.