When such anxiety-inducing numbers\u202fcome to our attention,\u202fit\u2019s\u202fworth pausing to ask a few questions.\u202fLet\u2019s\u202fstart with a basic one: how does a data centre even use water?\u202f <\/p>\n
![\"Data](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/06\/data-centre-in-the-netherlands-LG2KILA7EFDZJEQLRHWVK2NF3A.jpg\")
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Data centre in The Netherlands (Source: istock.com)<\/p>\n
A data centre is little more than a warehouse full of computers. Cram enough of these into a confined space and very quickly you have a problem with overheating. Air cooling works to a point, but water is often much more effective.\u202f <\/p>\n
An evaporative system is one cooling method, where water is sent into the atmosphere along with heat energy. Alternatively, there are more modern circulating systems, where the water is cycled through and piped back out as needed.\u202f <\/p>\n
The first point to make is obvious, but still worth\u202fmentioning: water\u202fis not destroyed by either process. Consumptive use of water, evaporation, still returns it to earth elsewhere. In non-consumptive, circulating systems, the water is available again\u202fimmediately.\u202f <\/p>\n
At first glance, most\u202fpeople will assume that the UN report is warning about water evaporated for cooling. But the volume used by these processes\u202fdoesn\u2019t\u202feven come close to the 1.3-billion-person figure. The UN report is concerned with the \u201cassociated water footprint\u201d needed to produce the electricity used by data centres.\u202f\u202f <\/p>\n
In many parts of the world, New Zealand included, power is produced by hydro. It is renewable, affordable, and dispatchable\u2014a wonderful bit of technology.\u202f\u202f <\/p>\n
A hydro dam uses water to spin a wheel, after which it flows away unharmed. The amount of water used is enormous, but\u202fit\u2019s\u202fnon-consumptive: downstream, it is available to use again.\u202f\u202f <\/p>\n
So\u202fwhat\u2019s\u202fthe problem\u202fwith the UN report?\u202f <\/p>\n
A hydroelectric system has a fixed amount of water available for electricity generation. That amount is\u202fdetermined\u202fby how much water flows into the catchment. If that water is not used to generate electricity, it passes through the system as spill. Reducing electricity consumption does not save the water for some alternative use. It must either be used to power something else or flow through unused.\u202f <\/p>\n
This means water use is already baked into the cost of hydroelectricity. It is not a separate line item. Complaining about both the electricity used by a data centre and the water used to make that electricity counts the same cost twice under different names.\u202f <\/p>\n
If the data centre disappears, you\u202fdon\u2019t\u202fget back both the electricity and the water\u2014you only get one.\u202f <\/p>\n
Even more importantly, water is not fungible. An extra litre of water in a Swedish hydro reservoir is entirely meaningless to a poor household in sub-Saharan Africa walking to their local well. No amount of Scandinavian water will help them.\u202f\u202f <\/p>\n
Of course, there are parts of the world where water is scarce, groundwater is overdrawn, and humans face risk of drought. Several American localities have mismanaged their natural water resources. But none of this is an AI-specific problem, and it is easily managed by boring, old-fashioned tools like resource management regulation and water rights.\u202f <\/p>\n
The UN report\u2019s invocation of sub-Saharan households is designed to provoke and outrage, not inform.\u202f <\/p>\n
But\u202fperhaps I\u202fprotest too much.\u202f1.3 billion is a big\u202fnumber \u2014 16% of the world\u2019s population.\u202fSo\u202fwhat is this figure as a percentage of total human water use?\u202f <\/p>\n
America has more data centres than any other country on earth, and they only use 0.2% of their total human water consumption. <\/p>\n
Even\u202fthe inflated \u201cassociated water footprint\u201d number from the UN forecast,\u202f3.7 trillion litres globally, is little more than double what California uses to grow almonds. <\/p>\n
The fact is that AI\u202fwon\u2019t\u202fbe causing us to drink out of our roof gutters. <\/p>\n