If you replace the area of that data center with apartments, as the question suggested, it would add half again to the local population, which could indeed use 30% of the city water.

I'm not understanding the logic. You want to add more population to the city? That doesn't seem fair but I'll concede I may not understand the point you're trying to make.

Assuming that the population is the same in the city and you just move residents into an apartment complex. I don't understand how you would get the same water consumption, am I missing something? Evaporative cooling is extremely water heavy and these facilities also have the normal HVAC you'd expect. Everything just seems to point to more water usage not less.