AI's environmental numbers, and why everyone's are differentPer-prompt water estimates for AI range from 0.26 mL to abou...

AI's environmental numbers, and why everyone's are differentPer-prompt water estimates for AI range from 0.26 mL to about 519 mL. That's a factor of 2,000. Neither is wrong — they're measuring different things.Google's 0.26 mL figure covers on-site cooling water for a median Gemini text prompt, including idle chips and data centre overhead. It excludes water consumed generating the electricity. The UC Riverside team's 519 mL figure is for a 100-word email and includes that indirect water. Google's own narrow, chip-only version of its methodology gives 0.12 mL. Sam Altman has cited ~0.39 mL for ChatGPT.So before repeating any per-query number, check what's inside the boundary.The aggregate pictureData centres used about 415 TWh in 2024 — roughly 1.5% of global electricity. AI-specific facilities used about 155 TWh in 2025, or about 0.5% of world electricity. That's the total-stock view.The growth view looks different. In 2025 data centre demand grew 17%, AI-focused facilities grew 50%, ...