Global data–water symbiosis reduces AI infrastructure’s carbon and water footprint

Data centres support artificial intelligence (AI) development but place rapidly increasing demands on electricity and freshwater resources, with cooling representing a significant portion of their total energy consumption. Wastewater treatment plants (WWTPs) discharge large volumes of treated effluent with substantial cooling potential; however, their integration with data centre infrastructure has not been evaluated. Here we construct a global geodatabase of over 4, 775 data centres and 57, 547 municipal WWTPs across 98 countries, integrating spatial analysis, engineering systems modelling, optimization, and life-cycle assessment to quantify the benefits of combining treated water reuse with bidirectional thermal recovery. The analysis reveals a strong global spatial co-occurrence between data centres and WWTPs, enabling optimized national-scale pairings in which treated effluent is used for data centre cooling and the return heat is recovered to support sludge drying and anaerobic digestion. This symbiotic approach reduces greenhouse gas emissions by approximately 84 million tonnes of CO 2 equivalent annually, conserves approximately 1, 300 million m 3 of freshwater, and provides net annual cost savings of approximately US95. 4 billion. The greatest mitigation and water-saving potential lies in the United States, Japan, China, the Netherlands, and the United Kingdom. These findings establish data–water symbiosis as a readily scalable infrastructure solution that decouples AI from its carbon and water footprints. WWTPs are poised to evolve from disposal facilities into critical energy-coupling hubs, enabling efficient thermal and water exchange across urban systems and accelerating progress towards multiple Sustainable Development Goals. • Data centers and wastewater treatment plants share complementary heating and cooling energy flows that remain globally underexploited. • Global data–water symbiosis could cut ∼84 Mt CO 2 eq annually while conserving ∼1, 300 million m 3 of freshwater. • Net economic savings reach ∼US95 billion annually, even without carbon subsidies or social-cost accounting. • 87. 8% of beneficial data–water linkages fall within 40 km, making near-term urban deployment feasible. • Strategic symbiosis between data and water infrastructure directly advances UN SDGs 6, 9, and 13 at the global scale.