There's nuance in that too. In the US, some farmers are subsidized to grow corn that is then turned into ethanol and burned as a fuel for cars.
Apparently, about a third of the corn grown in the US is for cars.
Another example. My province has a huge cranberry industry. The biggest in Canada. One can see the cranberry fields from satellite pictures. We don't eat that many cranberries. The vast majority is exported. We don't survive off them. Yet, this industry may deplete some rivers in central Quebec.
I don't want to seem like I'm defending the use of water by datacenters for stupid AI prompts. I'm just adding that we're also using lots of water to grow corn that's gonna be burned by a car.