Almost none of them run closed loop systems. They’re extremely expensive, and even if they did they actually still use just as much water, it’s just that the water is now being spent at a gas or coal power plant instead of on site due to the increased energy usage.
The systems that most data centers use are called adiabatic cooling systems. They evaporate water after a closed loop because the problem isn’t moving the heat away from the servers, it’s getting rid of them fast enough.
Conveniently most data center providers provide absolutely no statistics about these things because they look very bad to the public, but researchers have calculated usage.
https://www.washingtonpost.com/technology/2024/09/18/energy-ai-use-electricity-water-data-centers/
https://www.eesi.org/articles/view/data-centers-and-water-consumption