A Guideline to Evaluate Sorbent Performance for Atmospheric Water Harvesting

Access to safe drinking water is one of the most urgent challenges of our time. According to the United Nations (2023), more than 2 billion people still lack access to safely managed drinking water, and climate change is intensifying this crisis. Atmospheric water harvesting (AWH) technologies, particularly those based on solid sorbents such as activated carbons or metal–organic frameworks, have emerged as promising solutions capable of harvesting water even in arid and low‐humidity environments. However, the absence of standardized testing protocols and performance metrics has led to inconsistent and often noncomparable data across studies. Reported values for water uptake, regeneration energy, and cycling stability are frequently obtained under divergent conditions, limiting the practical evaluation of sorbent materials for real‐world deployment. This article proposes a unified and reproducible methodological framework for characterizing sorbents for AWH. By exploiting gravimetric and volumetric methods, as well as essential water quality metrics, seven key performance indicators are defined: water uptake capacity, humidity sensitivity, sorption/desorption kinetics, reversibility, regeneration conditions, long‐term stability, and the quality of water produced. This approach aims to accelerate the development and certification of AWH technologies by enabling clear, standardized comparisons between materials.