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Comment by alcomatt | Hacker News Reader

In some cases it does. Most of the DCs use open evaporators still. Keeps the costs down.

Yes and many forms of electricity generation evaporate water as well

Yes. The part I don't get is why do we care about that?

Earth is two thirds water, and it rains. The water I drank this morning is million of years old. It will be around for millions more.

So, they pump some water out of the earth and it evaporates... It will come back down, and we aren't running out anytime soon.

Why do we care? Are they building these things in deserts? If so that's the problem. They should use closed loops if they want to build in the desert.

This is satirical, right? They use fresh water, which is a tiny, tiny % of all water on earth.

2.5 to 3% according to google... Small but not tiny tiny

That's fresh water in general. Most of it is frozen. The amount you can actually use is a sliver.

Three percent of two thirds of the entire planet is enormous. We aren't running out, and never will.

Some people just live in places that aren't suitable for human life and survive only through technology. Those places need to have different laws about water.

For example, I shouldn't be forced to use a low flow showerhead when I'm 100 miles from 1.3 quadrillion gallons of fresh water. If you aren't next door to lake Michigan then maybe you should be.

Because you're the only person on earth who matters, clearly.

Also, it's not 3% of 2/3. It's more like ~1% of 3% of 2/3. Most of the fresh water on earth is locked up in glaciers or trapped deep underground. You can absolutely lose surface water, too - when pipes leak, for instance. And that happens all the time because a lot of the water infrastructure is ancient. Where I live, there are still thousands of miles of Victorian-era pipes. These crack all the time. You don't just get that water back straight away when it next rains.

> You can absolutely lose surface water,

Where the heck does it go? Space? You're talking about the entire planet here. There's nowhere for it to be lost to, unless you're cracking it into hydrogen and oxygen or something.

> Because you're the only person on earth who matters, clearly.

As I said elsewhere in this third 2/3rds of humans live near large bodies of water.

Your question is already answered in the comment you're replying to.

It's not. You say it's gone after the pipe leaks, but it's still on earth. I have no idea where you think it goes.

It goes into the soil and can take a long-ass time to get back into any our supply. Yes, it's still on earth, but it's no good to you if it's locked up in the soil or the polar icecaps. And that's not to mention the ridiculous ways we pollute water that make it very difficult if not impossible to recycle. This stuff really isn't as simple as just drain the lakes and rivers. We absolutely could run out of fresh water, and pumping it into data centres is a terrible idea.

> We absolutely could run out of fresh water, and pumping it into data centres is a terrible idea.

Maybe if you live in a desert. I'm not going to. We don't all live in the same place, and different rules are necessary. I suspect that much of the talk about evaporative cooling comes from treating places where it is sensible to do as if they are places where it's not.

There is a lake not far from that it would take about 3 days to cross on foot at it's SHORTEST point. Walking the full length would take about TWO WEEKS, someone would probably die of dysentery along the way.

Water scarcity is a regional problem that's being passed off as a universal concern for all of human-kind. It isn't. Earth has water, lots of it. Some places are just crummy places for humans to live.

Why does this matter? It remains fresh when its evaporated until it falls into the ocean, and then gets evaporated from there back into fresh.

It matters because there's almost none as it is, and you don't collect 100% of the water you use just because it rains. Water gets polluted, trapped underground, locked up in glaciers.

> It matters because there's almost none as it is

That's ridiculous and untrue.

Statistically speaking, compared to non-fresh water and compared to how much we actually use as a species, there is very, very little fresh water available to us.

I do need an entire ocean of water to live a normal lifestyle. Only some amount far less than the many, many, many quadrillions of gallons of freshwater we have.

If you live in the desert, stop doing that... or get them to laws for your specific place in the world. Where I live we have something close to an infinite supply of fresh water.

This attitude is why the world is fucked.

Because it rarely goes back to the place it has been taken from.

That doesn't matter though, what matters is that sources of freshwater (rain over land) stays roughly the same. We can't assume that changes just because we evaporate water in a data center

Ah ok, then drought aren't a problem I guess? Guess what happens when you pump ground water faster than rain water replenishes it? Guess what climate change is disturbing?

This your your typical HN take, aka "I thought about a random problem I barely understand for 12 seconds and I think I figured it out better than domain experts"

Fully two thirds of earths inhabitants live near large bodies of water. It's not a problem for most of us.

The 1/3rd that choose to live in arid places where droughts are a concern should probably just pass laws that require closed loop cooling.

There are plenty of places built around water for obvious reason which are now experiencing droughts at an increased rate... It's not a problem for most of us yes, but it's a problem for more and more people.

https://edition.cnn.com/2026/08/16/climate/lake-powell-reser...

https://www.dw.com/en/romania-shuts-nuclear-plant-hungary-da...

https://news.northeastern.edu/2026/06/17/colorado-river-desa...

> Fully two thirds of earths inhabitants live near large bodies of water.

Most of these large bodies of water are salty, it's expensive as shit to desalinate it completely infeasible to pump it in land for agriculture and people

It doesn't need to be desalinated for evaporative cooling, does it? Maybe they use fresh water because we allow it and it's cheaper. They should outlaw that where it makes sense.

Why would you bring sea water if you're hundreds of km away from the sea?

Either the entire world is stupid and has been for decades and you're a genius. Or your 5 minutes take on the subject is completely unrealistic and you're missing half of the story ?

1) I said that 2/3rds of all humans live near large bodies of water so evaporative cooling was probably fine for most of us.

2) You replied that it was saltwater and desalinating it was expensive.

3) I pointed out that saltwater evaporates fine. You seem to have assumed that cooling can only be done with freshwater for some reason.

4) You now seem to believe that I'm a simpleton who is suggesting that the people who live near large amounts of freshwater should also import salt water for some reason? Honestly I'm lost. They don't need to, they have fresh water which will also evaporate fine.

If water is scarce where you live, you live in a bad (and relatively rare) place that humans aren't meant to live. You should be talking to your representative to make sure data centers don't waste your imported water just because it's cheaper.

Everyone else will be fine.

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