Figure 1: Water is a precious resource, and modern data centers consume it heavily for cooling. Data centers worldwide use enormous volumes of water for cooling. Recent reports estimate that the global data center industry already withdraws about 560 billion liters of water per year datacenterdynamics.com (over half a trillion liters) and could double that by 2030. For scale, a single 1MW data center may use on the order of 25.5 million liters per year for cooling weforum.org – roughly the daily water consumption of tens of thousands of people. An average large data hall can use ~300,000 gallons per day (≈1.1 million liters/day) just for cooling news.lenovo.com. AI workloads are accelerating this trend: projections indicate that, by 2027, global AI-related data center cooling could require 1.1–1.7 trillion gallons of water per year (≈4.2–6.6 billion m³) weforum.org. These figures underline that every new AI or cloud installation significantly adds to the water footprint of computing. Moreover, many new facilities are being sited in water-stressed regions: roughly two-thirds of the data centers built since 2022 are in high-water-stress areas (e.g. California, Texas, Arizona, Illinois, Virginia) datacenterdynamics.com, raising local water security concerns. • Massive scale: Data centers withdraw on the order of 10^11–10^12 liters per year globally datacenterdynamics.com. • Per-center usage: A typical 100MW data center can consume ~2 million liters per day datacenterdynamics.com (≈730M L/year). • AI acceleration: High-performance AI clusters grow fast; e.g. estimates show AI training/inference driving water use to multi-trillion-gallon scales by late 2020s weforum.org. • Local impact: Some planned AI data centers have already faced community pushback over water (e.g. Google delayed a site in Chile due to aquifer concerns datacenterdynamics.com). Example calculation: A 100MW AI data center using 2,000 m³/day (≈730,000 m³/year) at roughly $1 per m³ of water would spend about $730,000 per year on water alone. Cutting that by 50% (through new cooling tech or reuse) saves on the order of $365,000 annually, illustrating the economic stakes of water efficiency. Data Center Cooling and Water Use Data centers consume water both directly and indirectly. Direct use comes from active cooling systems (cooling towers, evaporative pads, chillers) that evaporate or circulate water to remove heat. Indirect use comes from electricity generation: most power plants (especially thermoelectric ones) use large volumes of water to cool turbines. Thus, lowering electricity needs for computation or cooling also reduces water drawn by power plants news.lenovo.com. In most large facilities, the dominant cooling method is evaporative cooling. Traditional air- cooled servers reject heat into room air, which is then pushed through external cooling towers or pads. In these systems, warm water from indoor heat exchangers is sprayed over wet pads, and large fans blow ambient air through the pads to evaporate the water and absorb heat news.lenovo.com. The evaporated water is lost to the atmosphere and must be continuously replenished from the local supply. In practice this means millions of gallons per year per data center are consumed. One industry analysis notes that roughly 80% of the water used in an evaporative cooling system is lost to evaporation (the rest goes to blowdown/wastewater) datacenterdynamics.com.