How much water do these things actually use?
A lot, potentially. Large data centers use evaporative cooling systems that can consume millions of gallons per day. In The Dalles, Oregon, Google's water use grew from 104 million gallons in 2012 to 434 million gallons in 2024, eventually consuming roughly a third of the city's total water supply. In Mesa, Arizona, Google secured rights to up to 4 million gallons per day.
That said, facilities vary widely. Air-cooled and closed-loop systems use dramatically less water. The key is knowing which cooling technology a developer is proposing and whether there are enforceable caps written into the agreement. If the answer to either question is "we'll figure it out later," that's a red flag.