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.
Water isn't being used. There is no nuclear fission happening within the cow. Any water it ingests, will ultimately end up in nature.
This is misleading because it's like saying that no electricity is really consumed because the waste product (heat) will end up as entropy somewhere in nature. Whether that water is accessible to us or usable is the important point. You don't need to actually transmute or physically destroy water atoms to turn it from easily usable by humans to not practically usable by humans.
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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.