India, July 22 -- Sam Altman, chief executive of OpenAI, has called community concerns about AI data centres consuming water "insane". Scientists who study the question are less certain about almost everything else.

"We don't have the real ground-truth numbers on data-centre water use to put everyone on the same page," Eric Masanet, a sustainability researcher at the University of California, Santa Barbara, told The Atlantic.

This is the central problem. As AI drives expansion of server infrastructure, freshwater costs are substantial, contested and largely unknown.

Amazon's disclosure last month that its data centres consumed 2.5 billion gallons (about 9.5 billion litres) of water in 2025 - roughly 5% of Seattle's annual consumption -...