STRAIGHT ANSWER
Do closed-loop or 'zero water' data centers really use no water?
They can eliminate evaporative cooling water on site, which is a real reduction. They do not eliminate water used to generate their electricity, water used in construction, or water used to manufacture chips. 'Zero water' is a cooling claim, not a footprint claim.
The context
Microsoft says its AI-optimized design introduced in 2024 uses zero water for cooling during operations. Dry cooling usually trades water for more electricity, which carries its own indirect water, so the net effect depends on the local grid.
What this answer does not say
- That the site's total water footprint is zero.
- That 'liquid cooled' means waterless. The internal loop is closed; heat rejection outside it may still be evaporative.
- That dry cooling is always the better environmental choice; it can raise electricity use.