Why (on earth) does AI use so much water?
You’ve probably seen or heard of people getting annoyed at how much water AI appears to use - but why does it even need water in the first place and is this actually a problem?
Anytime you ask an LLM a question, somewhere in the world a computer gets hot. Your request is likely processed by a powerful computer in a data centre - thousands upon thousands of specialised chips & GPUs whirring away in enormous grey buildings performing quadrillions of mathematical calculations every second, creating the next cat meme (probably).
All that computation requires electricity. And almost all of that electricity turns into heat. Data centres are, effectively, enormous electric radiators.
The issue is that computers don’t like getting hot. Why? The main reason is that heat makes electronics less reliable and degrades performance. Chips have in built ‘thermal throttling’ capability to stop them effectively melting as they can easily get up to 90 degrees celsius. If you also let a data centre just heat indefinitely, the building would probably burn down - such is the amount of heat produced.
Put simply, the computers are absolutely roasting.
Water is very very good at cooling things down
There are a few different ways data centres use water to cool themselves but the main principle is evaporative cooling. When water evaporates, it absorbs heat from its surroundings. Like sweat cooling your body. Data centres pass enormous amounts of water around the chips (through closed pipes that is, not spraying them…you'd get fired pretty quick if you did that), which transfers the heat away from the chips & subsequently evaporates to remove the heat. You can get ‘closed loop’ systems where the water passes over the chips doesn’t actually itself evaporate, but that then still needs a heat exchanger which in turn requires secondary evaporation…. yada yada, I’ll spare the details.
Liquid cooling doesn’t automatically mean water is being consumed, but more often than not it is.
So how much water are we talking about here?
A lot. Estimates suggest direct water usage for cooling could reach 250 billion litres annually by 2028 - about 100,000 Olympic swimming pools. And then there’s ’indirect’ water usage - i.e. water used to cool power stations that provide the electricity to the data centres. Figures approach a trillion litres of water annually when you factor that in.
Should we be worried?
Worried… possibly. Angry? Well that depends on how much of an activist you are.
Let’s get things straight. Water is a renewable energy source - it doesn’t leave the planet (usually….) so it’s more a matter of how effective we are as a human race at capturing and circulating these water demands to everyone who really needs them. The UK for example is strongly scrutinising water usage by data centres (we are in the middle of a hosepipe ban…) and the tech companies are actively trying to innovate to bring water usage down (apparently….).
You can also use non-potable water, wastewater, and various other methods to try to reduce demand or processing required.
Right now, data centre water usage is a fairly small share of total demand - but therein lies the point. It probably won’t impact national supplies - but on a very hot day it might genuinely make a local water crisis worse. What's more important: getting water from your tap, or generating the next meme cat? (I mean, obviously the latter right). At any rate, there’s an uncomfortable irony in building enormous AI facilities in potentially hot & getting hotter, water-stressed regions, then using scarce freshwater to stop the computers overheating. In the UK, data centres use the same quality drinking water for cooling that we get out of our taps. Talk about service!
Anyway, all this water talk has made me thirsty. Let’s grab a cuppa and set my agents running…