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Comment by blkhawk | Hacker News Reader

what does "water used by data center" even mean? Does it consume the water somehow? What does it turn into? Steam? So uploading a 1GB file boils away nearly 1 liter of water? Or is it turned into bits somehow in some kind of mass to energy conversion? I sorta doubt that. Also this means data centers would have cooling towers like some power stations. Are we talking about the cooling towers of power stations?

I think at least that graph is complete non-sense. I will try and have chatGPT explain it to me.

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> what does "water used by data center" even mean?

This doesn't clarify what exactly it includes, but there are two main things that generally are included:

(1) Direct water use for cooling, (which, yes, ends up as steam rom cooling towers), and

(2) Water used in generating electricity consumed by data centers, which, yeah, is again evaporated in cooling towers.

I wrote the article. Water use is used really ambiguously by people talking about data centers and LLMs in general. To get the numbers I just took the estimated water used per kWh (https://www.sunbirddcim.com/glossary/water-usage-effectivene....) and multiplied it by the number of kWh used in data centers for different tasks

Yes, datacenters have cooling towers. There are lots of good articles about this topic. A good starting point is "water usage effectiveness" (WUE) which is one way this is tracked.

The one near here just has heat exchanges. But even if all the others use evaporators then potential water usage is extremely misleading because its not like the water is consumed - its just temporarily unavailable.

Also why doesn't uploading a 1GB file to my NAS boil a liter of water? are maybe all the switches and routers used between me and the datacenter water-cooled? I mean I can see such switches existing but I don't see them be the norm. Why doesn't the DSLAM on the Street outside emit steam. Is there maybe one bad switch somewhere that just spews steam?

What I am saying is that at least that graph is without further explanation... bad.

> The one near here just has heat exchanges. But even if all the others use evaporators then potential water usage is extremely misleading because its not like the water is consumed

Water consumption in all contexts is mostly fresh water returned from immediately usable form to either evaporation or the ocean. It is not "extremely misleading", because when it returns to immediately usable form by, e.g., precipitation, that's when new water is considered to be made available. The normal definitions are internally consistent and useful.

I did a bit of research and even water just "involved" in the process is counted as used in this context. For instance river water that is used for cooling and returned is counted.

I think these sort of graphs are simply misleading and should not be used.

Is that actually a common configuration? I could find very little on data centers being cooler by river water, and the few I found sounded like they were doing something novel.

Using natural water is more common in power plants, where the volume of water is sufficiently large to use concrete aquaducts and the precision of the temperature isn't as important. Most datacenter liquid cooling is treated municipal water with glycol additives to prevent corrosion and pump jamming.

> what does "water used by data center" even mean?

It’s referring to water lost to evaporation in evaporative cooling towers, both at the data center and at the power generating plant.

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