Data-centre cooling and water

What it is

Data centres cool servers by removing heat from processors. The dominant method, evaporative cooling, passes hot rack air through cooling towers where water evaporates and carries heat away. A large hyperscale facility running evaporative cooling consumes one to five million gallons of water per day, equivalent to a town of 10,000 to 50,000 people. The standard performance metric is Water Usage Effectiveness (WUE), litres consumed per kilowatt-hour of IT load; the industry average runs roughly 1.8 L/kWh, while best-in-class liquid-cooled facilities achieve below 0.2 L/kWh.

Three technologies reduce water intensity. Direct-to-chip liquid cooling pipes coolant directly to GPUs and CPUs. Immersion cooling submerges hardware in dielectric fluid, using almost no water. Closed-loop recirculation systems cut freshwater draw by up to 70% by reusing treated water rather than evaporating it. Adoption is accelerating because dense AI GPU racks, particularly Nvidia H100 and Blackwell clusters, generate heat densities that air-based evaporative cooling cannot handle efficiently. The four principal water consumers are Amazon Web Services, Microsoft Azure, Google Cloud, and Meta, which collectively operate several hundred hyperscale facilities globally.

History

Evaporative cooling became standard in US data centres by the late 1990s. Consumption grew slowly through the 2010s as virtualisation improved efficiency. The inflection arrived in late 2022 with the public release of large language models and the ensuing hyperscaler capital-expenditure surge. Google's reported water use at its data centres rose from roughly 4.3 billion gallons in 2020 to 6.4 billion gallons in 2023, a 49% increase in three years. Microsoft's consumption roughly doubled between 2020 and 2022. The first significant civic pushback came in The Dalles, Oregon in 2022-23, when residents won a public-records fight for Google's local water-use data.

Current state

US data centres consumed an estimated 163.7 billion gallons in 2021, the most recent year with comprehensive national data. In Northern Virginia, the world's densest data-centre cluster, facilities drew nearly 2 billion gallons in 2023, a 63% increase from 2019. Loudoun County alone accounts for roughly 900 million gallons from about 200 facilities. Texas data centres were projected to consume 49 billion gallons in 2025, with models pointing toward 399 billion gallons by 2030 at current build rates.

Roughly two-thirds of data centres built since 2022 have sited in water-stressed regions. In Spain, Meta's planned campus near Talavera de la Reina in Castile-La Mancha would draw more than 600 million litres per year from the Tagus River, a basin under European Union drought alerts; Amazon has requested a 48% increase in its Aragón water allocation (three facilities licensed for 755,000 cubic metres per year combined); and the city of Lleida banned data centres over water and energy concerns. In the United States, a developer sued California's Imperial Irrigation District for 260 million gallons per year of Colorado River water in June 2026 (see مطوّر مركز بيانات في وادي إمبيريال يقاضي للحصول على مياه نهر كولورادو), and Tucson, Arizona revoked water access for the Project Blue complex after the city council refused to extend supply in May 2026 (see توكسون تقطع المياه عن مشروع بلو في خضم معارك مراكز البيانات على المياه في أريزونا).

Relationships

The water story connects to the broader data-centre energy and land footprint in AI data centres: global power demand. Energy and water are coupled: evaporative cooling also consumes electricity, so the shift to liquid cooling reduces both. Colorado River reallocation proceedings under the US Bureau of Reclamation now include data-centre applicants alongside agricultural and municipal claimants. Spain's conflicts (see الداخلية الجافة في إسبانيا تقاوم: مجمع «ميتا» في تالافيرا وموقع «أمازون» في أراغون) reflect a wider European pattern where drought-stressed regions in Iberia, southern France, and Italy are also major data-centre build-out targets.

What to watch

• Whether liquid and immersion cooling adoption reduces industry WUE fast enough to offset volumetric facility growth in the late 2020s.
• US Colorado River compact renegotiations, and whether regulators impose explicit priority rankings between agricultural, municipal, and data-centre water rights.
• Spain's proposed royal decree requiring energy and water reporting from facilities above 500 kW, and whether a future EU Data Centre Directive adds binding WUE limits.
• India and Southeast Asia, both fast-growing data-centre markets and home to some of the world's most water-stressed river basins, as the likely next front for water-rights conflicts.