Water footprint of China’s coal mining sector substantially underestimated

• Develops China’s coal mining water footprint framework based on 12,378 coal mines database. • Identifies 10.58-fold disparities in water footprint intensity across 208 technological configurations. • Demonstrates spatial mismatch: concentrated production vs. nationwide consumption. • Highlights prioritized COD, SS, BOD 5 , and heavy metal control throughout whole life cycle. • Quantifies technological structure, supply structure, and consumption demand as key transition drivers. China faces severe water scarcity intensified by the spatial mismatch between coal reserves and water resources. Accurately assessing the water footprint of coal mining is essential for quantifying water-related risks and guiding sustainable practices. However, existing studies often lack systematic frameworks that integrate grey water footprint accounting for heavy metals and other pollutants, leading to impact underestimation. To address this gap, we develop a comprehensive water footprint assessment framework based on an improved method incorporating 16 pollutants. It employs spatial analyses, long-term trends, and both production- and consumption-side perspectives, using data from 12,378 coal mines operated during 2013–2022. Key findings indicate that water footprint intensities vary from 3.16 to 33.44 m 3 /t across 208 technological configurations, with grey water contributing over 85 %. Large-surface mines show the lowest intensity, highlighting their water-saving advantage. Over the decade, China’s coal production water footprint intensity declined by 17.76 %, while the consumption-side fell by 16.75 %. Total water footprint for coal production and consumption decreased from 43.5 Gm 3 to 38 Gm 3 . Virtual water flows primarily follow a north–to–south and west–to–east pattern, peaking between Shanxi and Hebei (>1 Gm 3 ). Technological advancements reduced the national consumption-side water footprint by 7.99 Gm 3 . Supply chain optimization drove greater reductions in Fujian, Hunan, Jiangxi, and Chongqing. By rectifying grey water footprint underestimation and emphasizing heavy metal control, this study provides a scientific basis for spatially targeted water governance and cross-regional ecological compensation. The proposed framework has broad international applicability, especially for regions facing similar coal-water conflicts.