Under reasonable assumptions, the apartments would use more water.
- Google's datacenter complex in the Dalles covers ~190 acres.
- Typical density for apartment buildings is 50 units/acre, meaning you'd have 9,500 units on 190 acres.
- Average household size in the US is 2.5, so the 9,500 units would have a population of 23,750.
- According to the original article, per capita domestic water usage in the U.S. is 82 gallons per day, meaning a total water consumption of 710M gal/yr for the apartments. And this doesn't count the substantial indirect water usage you'd need to support this population.
- The Google datacenter uses 355M gal/yr (per the Oregonian article).
- 710M > 355M
Now, it would be somewhat ridiculous to replace the entire Google datacenter with apartment buildings in a rural town with declining population, but that was the original question...
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.