Direct Onsite Water vs Indirect Water
Two different quantities are both called 'data center water use'. Comparing a figure of one type with a figure of the other is the most common error in this debate.
Direct (onsite)
Water drawn at the facility for cooling and building services — usually from a municipal supply, sometimes from groundwater, sometimes from a reclaimed (non-potable) supply. This is the figure a local utility or a county board can see.
Indirect (embedded in electricity)
Water consumed by the power plants generating the electricity the site buys. Thermoelectric generation — coal, gas, nuclear — uses cooling water of its own. This water may be consumed hundreds of miles away, in an entirely different basin.
Withdrawal vs consumption
Withdrawal is water taken from a source; consumption is water not returned to it. A once-through system may withdraw enormous volumes and consume little; an evaporative tower withdraws less and consumes most of what it takes. Headline numbers frequently do not say which one they are reporting.
Why this matters for the investigation
A site can honestly report near-zero onsite water while carrying a real indirect footprint, and a site can report high withdrawal while returning nearly all of it. Any site entry in this quest must record which measure it is using.