Google's 10.9 billion gallons: the water story inside the AI boom

The number

Google's 2026 environmental report records freshwater consumption of 10.9 billion gallons in 2025, a 34% increase on 2024 and more than double the 2021 figure. Data centres accounted for most of the growth. In metric terms it is about 41 million cubic metres, roughly a third of what TSMC's entire chip-fabrication estate consumed in 2024.

Why it rose

Google's fleet cools largely by evaporation. Its disclosed water-use effectiveness is 1.15 litres consumed per kilowatt-hour of IT electricity, several times the figure AWS (0.15) or Microsoft (0.30) report, and the price of a world-class PUE of 1.10. When electricity consumption rose 37% in 2025, water followed. There is no efficiency trick that breaks the link short of redesigning the cooling, which Google has not announced doing at fleet scale.

Replenishment

Google's stated goal is to replenish 120% of the freshwater it consumes by 2030, through projects that restore watersheds or return water to stressed basins. The company reports it reached 64% in 2024 and about 78% in 2025, replenishing roughly 7.7 billion gallons. Those are real projects, and the index credits them in the water pillar. Replenishment does not, however, return water to the aquifer a particular data centre drew from, and it does not reduce consumption.

The per-prompt view

The same company measured 0.26 mL of water for a median Gemini prompt, about five drops, counting on-site cooling only. Critics noted the figure excludes water consumed generating the electricity, which on the US grid adds roughly 1.8 litres per kilowatt-hour, several times the on-site amount. Both the five drops and the 10.9 billion gallons are correct. The first is the cooling cost of one prompt; the second is the cooling cost of all of them, plus training, plus everything else Google does.

What the index scores

The water pillar gives Google 55: a disclosed WUE and a serious replenishment programme on one side, rising consumption, a high WUE and the history at The Dalles on the other. Sort the rankings by WUE to see how unusual Google's design choice is among companies that disclose at all.