[eel]

Evaporative cooling (like a "swamp cooler" for residential homes) is how most data centers in the US are cooled. The water is primarily consumed by evaporation. When you continually evaporate water from a system, eventually the remaining water in the system gets concentrated in salts and other minerals and is dumped and replaced with fresh water.

Much of the day/season, evaporative cooling is not needed and data centers can pull in outside air. Ultimately you state the main reason in your comment: using outside air + evaporative cooling is cheaper and consumes less power than any other approach.

In a lot of cases, even if the server chips themselves are liquid cooled (for example, in an NVIDIA GB200 rack), then liquid is then air cooled through a cooling distribution unit (basically a giant radiator.