Do closed-loop geothermal systems at data centers use a lot of water?

No.

Closed-loop geothermal cooling systems are engineered to minimize water usage.

These systems circulate sealed fluid (typically water or a water-antifreeze mix) through buried pipes or geothermal heat pump loops. The same fluid continuously transfers heat between the ground and the data center without evaporation or release. Only the initial fill and occasional top-off to replace minor losses due to leaks are required. Unlike evaporative cooling towers that consume large volumes of water, closed-loop systems return all water to the system, making ongoing use negligible. Studies show that data centers adopting closed-loop and water-less cooling methods significantly reduce water use, with many facilities using less water than typical non-data-center buildings. This makes closed-loop geothermal attractive to operators in water-scarce regions and aligns with industry moves to conserve both energy and freshwater resources.

This fact brief is responsive to conversations such as this one.

Sources:
U.S. Department of Energy: Geothermal Heat Pumps
International Renewable Energy Agency: Renewable Energy in Cooling
Environmental and Energy Study Institute (EESI):  Data Centers and Water Consumption
Rhodium Group: Geothermal Data Center Electricity Demand
Equinix: How Data Centers Use Water, and How We’re Working to Use Water Responsibly