Sustainable management is the keyword for the future. In the world of water engineering, the constant increase of water demands from agriculture, from humans, due to climate change and socioeconomic factors, is forcing researchers to deal with the demanding request to optimize as much as possible the management of the available water resource. In this context, the era of Big Data and Machine Learning provides innovative ways to accomplish a more sustainable future. The techniques to manage the water resource and to solve problems of water engineering have undertaken an important renewal process in the last years that aims at providing novel and more efficient solutions. The reason of these demanding transition into a more sustainable and smart management paradigm lies in the climate change that is facing our planet, which will keep increasing the global water demand. A combination of both water resources and water demand management strategies is necessary in order to adapt to a varying environment and the associated uncertainties. As results, new challenges related to water-energy nexus and energy recovery are rising in this new era and are demanding for sustainable and eco-design solutions, due to restrictions imposed by climate change, requiring more flexible and new adaptive answers.