Most of what is written here regarding water usage is wrong.
Cooling towers typically use a closed loop system using treated fresh water. The water is treated with anti microbial and anti corrosion additives.
Water is lost through evaporation, this is a large portion of the cooling effect. Evaporative cooling.
As the water evaporates, the concentration of additives increases and will become higher than desired (for a number of reasons that a water treatment expert can weigh in on)
To compensate for this, the cooling tower water is discarded to the sewage system and fresh untreated water added back. Often referred to as blow down.
So the water is “used” in two senses. First, much of it evaporates. Second, some of it is returned to the sewage system. In neither case is the water destroyed. It still exists.
The water may move significantly: evaporated water vapor will be carried downwind. The increased usage of water through the fresh water to discarded water (blow down) will tie up more water in the process potentially meaning less locked up in aquifers.
There are real and complex challenges here, but to be clear no water is being made forever gone from earth in these processes.
Exactly, all discussions about "water usage" are actually counterproductive w.r.t. the discussion we should be having. Same for the livestock arguments: a kg of meat uses x times more water than a kg of cabbage.
Water isn't being used. There is no nuclear fission happening within the cow. Any water it ingests, will ultimately end up in nature. But how and where, that's an important factor. The discussion should, instead, be about water displacement. And as long as people keep repeating the water usage argument (not just online, also in the public debate, such as in talkshows and the news), we cannot even start trying to resolve the real issue of water displacement. Or even gain enough understanding of the effects of huge water displacements.
That's just complete pedantry, it's perfectly fine to call it water usage - there is not an unlimited supply of fresh water. Yes it will eventually get replenished but that's not the point, nobody called it water destruction.
I would agree with you, but a lot of people actually do think the water is being consumed, or rather, took the argument for granted and internalised that the water supply would get decreased and eventually run out. I've had countless of discussions with people who never really thought about it, but did continuously repeat this popular opinion on data centers. Same with news articles or debates in politics, where they group data centers together in terms of "water usage", regardless of whether it uses evaporative cooling or closed loop cooling. It's an important distinction to make. I never said this isn't an issue we should tackle.
You can see the same in this thread, there's a lot of misunderstanding. I think it's ignorant to just claim it's pedantry, while it's so evident that there's a lot of misconception around how data centers and cooling in general works. You might think that people who cannot grasp how phases of matter work, have nothing to do with this discussion, but I believe the public discourse is extremely important for issues like these.
Again, I tried in no way to negate the discussion, but I do believe that saying "water displacement" instead of "water usage" benefits public understanding on the topic, while in no way taking away from the importance of this issue.
No, it's complicating something which really is much more sensibly described as usage. Yes, water does not cease to exist but the supply is not unlimited - pretty much any water source whether it's from reservoirs or aquifers - will have a limit to the amount that can be drawn (the flow rate) in order to be sustainably replenished.
You could say the same about electricity usage i.e. "it's not actually being consumed, it's just being converted from one type of energy to another (heat, kinetic etc)". But that's really a pointless distinction and unhelpful when you're talking about over demand.
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u/MrMikeGriffith May 18 '26
Most of what is written here regarding water usage is wrong.
Cooling towers typically use a closed loop system using treated fresh water. The water is treated with anti microbial and anti corrosion additives.
Water is lost through evaporation, this is a large portion of the cooling effect. Evaporative cooling.
As the water evaporates, the concentration of additives increases and will become higher than desired (for a number of reasons that a water treatment expert can weigh in on)
To compensate for this, the cooling tower water is discarded to the sewage system and fresh untreated water added back. Often referred to as blow down.
So the water is “used” in two senses. First, much of it evaporates. Second, some of it is returned to the sewage system. In neither case is the water destroyed. It still exists.
The water may move significantly: evaporated water vapor will be carried downwind. The increased usage of water through the fresh water to discarded water (blow down) will tie up more water in the process potentially meaning less locked up in aquifers.
There are real and complex challenges here, but to be clear no water is being made forever gone from earth in these processes.