Unconventional Water Resources: Opportunities, Challenges and Solutions for Water Management

Water resources are suffering from overexploitation in many parts of our world. This situation is exacerbated by climate change and the overuse of water resources in agriculture and industry. How to address this problem? Only a change in the main paradigms that govern the use of water resources, moving from a linear use of water to a cyclical management (with a vision close to that of the circular economy), can provide a solid answer to this problem. New technological, social, industrial and scientific challenges are directly linked to this new approach in water management, with the main idea that water is a resource too precious to be used without the right attention. In this short introduction to this SDG talk, I will provide an overview of the unconventional water resources, introducing the main topics that the other speakers will explore in depth.

Water is essential for life and plays a crucial role in human health and ecology. Despite Earth's high water availability, only a small fraction is readily accessible freshwater, which is vital for human needs. This limited resource is renewable and is recharged through natural processes such as precipitation and infiltration. The growing anthropogenic pressure on the planet has led to a global water crisis, exacerbated by climate change, pollution, over-extraction, drought, salinization, and water losses. Water consumption is dominated by agriculture (69%), followed by industry (19%) and domestic use (12%), with global demand projected to rise by 1% annually, particularly in emerging economies. Addressing these challenges requires a holistic approach integrating science, technology, and cooperation. Urgent and innovative actions are necessary to secure freshwater resources for future generations amid increasing environmental stress.

Global water resources show that many regions face water scarcity, driven by increasing demand due to population growth and rising human activities that require water. Simultaneously, climate change worsens extreme weather events, making water availability more unpredictable, while widespread pollution threatens water quality. In this scenario, effective water resource management is critical, and the use of unconventional water resources is gaining importance. These resources have significant potential to supplement traditional freshwater supplies with both qualitative and quantitative benefits. Twelve different types of unconventional water resources will be presented, examining their key characteristics, potential, and limitations. These resources are categorized based on their origin into four groups: (i) Atmospheric Unconventional Water (AUW); (ii) Processed Unconventional Water (PUW); (iii) Transferred Unconventional Water (TUW); (iv) Unconventional Groundwater (UGW). Currently, a global map of these resources is not available, although regional data can be found in the literature. With advances in artificial intelligence and machine learning, it is hoped that multi-component models can be developed to collect and classify available data, aiding decision-making. This will be vital for effective water resource planning, helping to address water scarcity and mitigate the impacts of climate change.

EU has bet for the reuse of reclaimed water as a key point for the sustainability. But, in the practice, expectations are not being met and the use of reclaimed water is very low. Murcia Region is the driest region in Europe and, at the same time, more than 2,6 million of agricultural products are produced every year in the Region, being the water a crucial item in our Region. Reclaimed water is an usual water source in Murcia Region since many years ago, with more than 110 Hm3 of reclaimed water being used every year, mainly in agriculture.The experience of Murcia Region can be a good opportunity to know the drivers and barriers of the water reuse.