As global environmental, social, and governance (ESG) initiatives reach unprecedented levels of corporate commitment, one critical challenge has continued to evade rigorous scrutiny: water sustainability. Despite the growing sophistication of carbon emissions tracking in corporate disclosures, water stewardship remains inadequately addressed and often cloaked in nebulous qualitative reports. This persistent oversight undermines the credibility of ESG efforts and presents a formidable barrier to achieving comprehensive sustainability goals. Recognizing this gap, an interdisciplinary team of researchers led by Professors Yong Sik Ok of Korea University and William Mitch of Stanford University has introduced a groundbreaking quantitative framework to revolutionize how industrial water use sustainability is measured and reported.
The newly developed Water Sustainability Index (WSI) emerges as a pivotal tool designed to bolster transparency and accountability in corporate water management. Published in the esteemed journal Nature Water on February 10, 2026, this index transcends the limitations of existing ESG water metrics, which often lack uniformity and are susceptible to inconsistencies and greenwashing. The WSI quantifies water sustainability by incorporating multiple variables, including water withdrawals, consumption rates, discharge quality, and reuse practices, while critically integrating local watershed-level scarcity factors. This multidimensional approach is tailored to tackle the inherently local nature of water resources in stark contrast to the global scale of carbon emissions.
Current ESG water reporting practices have been criticized for their overreliance on broad, qualitative narratives that fail to capture the nuanced realities of water usage across diverse geographic contexts. Prof. Yong Sik Ok highlights the fundamental difference between carbon and water as environmental indicators, emphasizing that water’s localized scarcity dynamics demand metrics that are sensitive to regional hydrological stresses. The research team’s analysis of the London Stock Exchange Group database reveals a troubling disparity: while 14% of prominent corporations disclose greenhouse gas emissions, only 9% report total water withdrawals, and a mere 1% provide data on recycled water. This transparency gap not only diminishes the perceived importance of water stewardship but also leaves significant room for misrepresentation.
The WSI addresses this problem through an innovative weighting scheme that prioritizes water use in regions experiencing high water stress, defined as areas where water withdrawals surpass 40% of the renewable freshwater supply. By assigning heavier weights to operations reliant on groundwater—sources more challenging to replenish than surface water—the index encourages companies to reexamine their water sourcing strategies. This nuanced approach acknowledges that identical volumes of water withdrawal carry vastly different environmental impacts depending on local scarcity conditions, thereby promoting more responsible water use and investment decisions aligned with the United Nations Sustainable Development Goal 6 (clean water and sanitation).
Importantly, the index is not a mere theoretical exercise but a practical tool for corporate decision-making. Through sophisticated computational simulation and scenario modeling, the WSI allows companies to evaluate and compare the sustainability outcomes of various operational choices before committing capital. For instance, the research team illustrated seven theoretical scenarios demonstrating the profound influence of location, technology, and reuse on a facility’s score. An operation extracting groundwater from a stressed watershed and releasing poor-quality wastewater scored a low 1.17, signaling considerable sustainability risks. Conversely, implementing internal process water reuse and upgrading wastewater treatment boosted the score to as high as 3.0, indicating significant improvements.
This ability to conduct proactive scenario testing empowers corporations to identify targeted, cost-effective interventions that enhance water sustainability. By quantifying improvements and penalties through a unified metric, the WSI provides a clear incentive structure—rewarding efficiency, reuse technologies, and superior wastewater management while penalizing unsustainable withdrawals. This transparent and repeatable scoring mechanism addresses the problem of ESG rating inconsistencies, where companies have historically received divergent grades from different rating agencies due to opaque methodologies.
Professors Mitch and Ok envision the Water Sustainability Index as a crucial bridge between the intricate scientific water footprint assessments established by frameworks like ISO 14046 and the practical demands of corporate ESG reporting. By simplifying complex hydrological and ecological data into a single reproducible score, the WSI facilitates comparability across companies and sectors, reducing information asymmetries that have long frustrated investors and regulators. This novel approach reflects a growing recognition that high-quality, data-driven sustainability metrics are essential to scaling impact investment and driving meaningful environmental improvement in industry.
The urgency of integrating water-related metrics into ESG frameworks intensifies amidst mounting global water stress, with approximately 25% of the world’s population currently residing in regions classified as extremely high-stress watersheds. This escalating resource pressure underscores why transparent and quantitative water assessments have become indispensable. Professor Jay Hyuk Rhee from Korea University, also a prominent figure in the International ESG Association, stresses that without rigorously standardized water metrics, companies risk perpetuating “greenwashing,” thus undermining both their reputations and broader global sustainability efforts.
The collaboration spearheaded by Korea University’s Prof. Ok and Stanford’s Prof. Mitch, with input from Prof. Rhee and the International ESG Association, underscores the value of cross-institutional research networks in addressing complex sustainability challenges. Their work exemplifies how integrating scientific rigor, computational modeling, and practical corporate governance considerations can create transformative tools to reshape global environmental policy. The WSI, now formally published and accessible, sets a new benchmark for industrial water use assessment, promising enhanced environmental stewardship and contributing substantially to the achievement of UN SDG 6.
As the ESG landscape continues to evolve, the Water Sustainability Index offers a blueprint for a more accurate, equitable, and actionable approach to corporate water management. By shifting the conversation from vague water-related commitments to concrete, location-sensitive sustainability scores, this breakthrough metric equips stakeholders with the knowledge needed to hold organizations accountable and prioritize water-efficient operations. It signals the emergence of a new era in which water usage transparency is no longer a blind spot but a cornerstone of credible and effective sustainability reporting.
In the years ahead, widespread adoption of the WSI could catalyze a profound transformation in how companies, investors, and regulators perceive and manage water risks. The index’s capacity to harmonize scientific detail with ESG compliance requirements enhances not only corporate reporting accuracy but also policy-making and investment prioritization. As global water scarcity and environmental pressures mount, tools like the WSI will be essential in safeguarding freshwater resources and ensuring that industrial development coexists sustainably with ecological preservation and social well-being.
Ultimately, the Water Sustainability Index embodies a decisive advance in the quest for comprehensive ESG metrics—one that acknowledges water’s unique challenges and integrates them into practical sustainability frameworks. With its transparent, multidimensional, and locally sensitive design, the WSI represents a compelling step forward toward a future where water stewardship stands on equal footing with carbon management, enabling more responsible corporate practices and fostering global environmental resilience.
Subject of Research: Not applicable
Article Title: A quantitative metric for industrial water use sustainability for environmental, social and governance reporting
News Publication Date: February 10, 2026
References: DOI: 10.1038/s44221-025-00575-9
Image Credits: International ESG Association
Keywords: Water, Sustainability, Environmental policy, Business, Environmental sciences, Climate change, Public policy, Sustainable development, Earth sciences
