Why do AI data centers use so much water, and which cooling approaches reduce water use?

Data centers consume significant amounts of water primarily for cooling systems designed to keep servers within safe operating temperatures.

Why Data Centers Use So Much Water

Most traditional large-scale data centers use evaporative cooling. This process works by passing hot air over water; as the water evaporates, it absorbs heat from the air, cooling it down before it is circulated back through the server racks.

This method is highly efficient in terms of electricity, but it is "water-intensive" because it requires a constant supply of fresh water to replace what is lost to evaporation. In regions with high temperatures or humidity, the volume of water required to maintain stable operating conditions for high-density AI hardware can be substantial.

Approaches to Reduce Water Use

Data center operators are increasingly turning to alternatives that decouple cooling from water consumption:

• Closed-Loop Liquid Cooling: Instead of relying on evaporation, these systems circulate specialized coolants (or water) through pipes that come into direct contact with the server hardware. Because the liquid stays within a sealed system, it is not lost to evaporation.
• Direct-to-Chip Cooling: This is a form of liquid cooling where cold plates are placed directly on the hottest components, such as GPUs and CPUs. By cooling the components directly, it significantly reduces the need for the large, water-heavy air conditioning units that cool an entire room.
• Immersion Cooling: Servers are submerged in a thermally conductive, non-conductive dielectric fluid. This fluid is much better at transferring heat away from components than air, and the heat can then be removed using a dry cooler, eliminating the need for evaporative water usage.
• Dry Cooling (Air-to-Air): These systems use large fans and heat exchangers to cool data centers using only ambient outdoor air. While this eliminates water use, it is often less effective in hot climates, as it requires the external air temperature to be low enough to cool the equipment effectively.
• Water Recycling and Reuse: Some facilities are designed to use non-potable water, such as treated wastewater (reclaimed water) or harvested rainwater, to meet their cooling demands, reducing the strain on local municipal drinking water supplies.

The choice of cooling approach is often a balance between energy efficiency (PUE - Power Usage Effectiveness) and water efficiency (WUE - Water Usage Effectiveness), as systems that prioritize one often require trade-offs in the other.