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Comment by avalys | Hacker News Reader

Is this water even “used” in the same sense that water is used for bathing or agriculture?

Where does the water go? If they simply take in cold water and release hot water, that water is still available for other uses.

Or do data centers use evaporative cooling just like power plants?

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> Or do data centers use evaporative cooling just like power plants?

Yes. Not always, but evaporative cooling is much more energy efficient than heat exchange to outside air.

That said, stories about data center water use are a distraction from much bigger water consumers like golf courses and agriculture (e.g. to ship alfalfa to the middle east).

> That said stories about data center water use are a distraction from much bigger water consumers

That's something of a fallacy of relative privation. When water is scarce, all frivolous uses should be under scrutiny. The others you mention have been well-known for a long time. The current stories simply highlight a new consumer people haven't thought of before.

Also - Will data center water usage remain "negligible" if AI succeeds at wide adoption and scales to 100x current deployment? If 100x current usage levels become a concern, I don't know why people pretend that current usage is not a concern for a tech that many of those same people are projecting to scale.

>Also - Will data center water usage remain "negligible" if AI succeeds at wide adoption and scales to 100x current deployment?

Yes.

I don't think it's a fallacy, it's much easier to optimize water usage for something that much larger.

Agriculture uses about 70% of all freshwater while datacenters are less than 0.5%

Some leaky channel will cost more than all the datacenters.

Even in case of evaporative cooling the water is not used. It's returned to the environment.

While technically true, if your datacenter is in Phoenix and you just consumed a few acre feet of water to raise the relative humidity by 0.000001%, for all intents and purposes that was a massive waste of water.

The problem with data center water usage is that it is unnecessary from the PR point of view. Data centers can run on air cooling just as good, but more expensive. For all I know, we could also do just as good without data centers, like we did 20 years ago.

With agriculture, water usage is necessary as eating is not something optional and everyone needs to eat to survive. From the PR point of view, of course. We couldn't live without agriculture, as we had agriculture 20 years ago too.

Golf courses are unrelated as they don't use nearly as much water as agriculture or data centers.

PR is everything, the narrative is what makes the difference. There is a lot of hypocrisy in this field, which is why I try to avoid it, but there is also some truth in it - we really didn't need that many data centers 20 years ago.

> Data centers can run on air cooling just as good, but more expensive

"More expensive" means spending more on air conditioning. Ergo more electricity used, higher electricity demand, more natural gas burned and carbon emissions, higher consumer power prices. So a different kind of PR disaster.

The difference in energy usage won't be noticeably higher for PR purposes. Of course, the difference comes at a price, cutting which is the main incentive for water usage.

OK, so we need to include the effect of introducing a green house gas, water vapor, into the environment.

Golf course water usage vastly dwarfs data center water usage. Google used something like 1 billion gallons a year for their DCs. Single golf courses in arid regions can use upwards of a hundred million gallons a year, and in those areas there can be dozens of courses. It's not even close in terms of water usage.

Golf courses in the USA used about 2.1 billion gallons of water per day circa 2004 [1]. In other words, the annual usage of Amazon's datacenters per the article, 7.7 billion gallons, is less than the amount of water used on just American golf courses in four days.

[1] https://www.usga.org/content/dam/usga/pdf/Water%20Resource%2...

If the data-center depletes the water table used for surrounding wells, whether the "released water" is still "available" is irrelevant to those dependent on wells for water.

e.g. https://www.nytimes.com/2025/07/14/technology/meta-data-cent... https://www.bbc.com/news/articles/cy8gy7lv448o

> Where does the water go? If they simply take in cold water and release hot water, that water is still available for other uses.

Well, first you need to cool it down in a way that's good for the environment, I presume. You should not pour down hot water in a cold river with all its fishes and plants.

Datacenters can use a few different kinds of liquid cooling, including the one you describe. It varies quite a bit by geography.

Even if it's evaporative cooling, couldn't the water vapor just be... condensed back into water?

Yes - by cooling it. See the problem?

You don't have to use energy to cool it though do you?

Couldn't it just flow into a big passive outdoor radiator?

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