Koomey Analytics is the site of Jonathan Koomey, an independent energy researcher who writes about data center efficiency and the environmental effects of computing; the site also lists a roster of corporate clients, which is worth knowing going in.

This particular post is an announcement rather than the study itself: it introduces a new white paper on data center onsite water use, and the operator-by-operator numbers live in that linked paper, not on this page. What the post delivers directly is a clear definition of Water Usage Effectiveness (WUE), the metric used to compare cooling water intensity across facilities. WUE is expressed as water consumption or withdrawals in liters divided by computing electricity consumption in kilowatt-hours, and Koomey notes it can be reported on either a consumption basis or a withdrawal basis — a distinction that changes what a given number actually means.

The post also names its data source: company-reported fleet-average figures for the top twenty global data center operators, ranked by Data Centre Magazine in 2025, with numbered references backing the claims rather than bare assertions. That sourcing discipline is useful on its own, even before a reader follows the link to the underlying white paper.

Come to this page for the definition and the framing around WUE, not for a ranking table of operators — that is the honest description of what you will actually find here, and it suits readers who want the metric explained before they go looking for the numbers.