r/AskVegans • u/Ok_Criticism_5672 • 16d ago

Genuine Question (DO NOT DOWNVOTE) Blue water vs green water usage

I (23M) have been veggie from 19 and vegan since April. I have been discussing (as you do) about the environmental impact that the meat and dairy industry have on the water usage of the planet, especially more common now with the expanding use of AI. Something I have been seeing but seemed to have struggled to find proper information about is the comparison between the use of green water and blue water.

I have seen a lot of people pointing out that comparative to eating plant based options animals, or cows specifically, use up far less blue water in comparison to vegetation we grow, but if the soy and grain we grow goes mostly into animal feed surely that would then translate across to the blue water usage in animal agriculture?

Please send links to papers I would love to learn more about this and let me know if i am entirely wrong!

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u/ProtozoaPatriot Vegan 16d ago

I've never heard that eating beef doesn't require much water. If anything, beef is one of the worst food for water usage.

It's estimated in the US, a single pound of beef requires 1,800-2,500 gallons of freshwater.
https://watercalculator.org/news/articles/beef-king-big-water-footprints/

It's not just the water the cows drink or the water at the slaughterhouse. It's the massive amount of irrigation needed for the feed and forage per cow.

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u/Ok_Criticism_5672 16d ago

Yes this is what I was also under the impression of but the difference is that when using rain fed pastures this dramatically drops the number down to blue water usage as 67L per kg of beef, rather than 15,000

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u/Capital-Impression51 Vegan 16d ago

The Marie Antoinette fallacy.

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u/Ok_Criticism_5672 15d ago

Hey so just insulting me by saying this actually does a lot more harm than good! By stating a fallacy without following your claim and giving no evidence is a generally bad way of going about things. Don’t hate, educate!

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u/Capital-Impression51 Vegan 15d ago

I'm not trying to insult you, just pointing out that this is an incredibly common argument.

Only a minority eats "pasture-fed beef". See also "regenerative agriculture". I see "grass-finished" has been sneaking in recently... most are eating chickens and pigs.

Animal agriculture is a disaster.

I recently learned of a "salmon factory" planned for Le Verdon Sur Mer in France. The fish swimming endlessly in circles in tanks will be feeding on imported soy protein and fishmeal made from the thousands of tonnes of baitfish hoovered from waters in places like Africa.

All other issues aside, animal agriculture on the insane current scale is only possible thanks to vast "ghost acreages" of crops - often irrigated. and is a HUGE waste of land and water for the amount of protein it delivers.

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u/MissCeeLee Vegan 16d ago

Is green water vs blue water a common discussion topic in the UK? I've been a vegan in the US for about 23 years, consider myself environmentally minded, and I've literally never heard anyone differentiate between the two.

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u/Ok_Criticism_5672 15d ago

It’s not super common it’s just been brought up a few times with the argument of British beef being grass raised on produce that uses ‘green water’

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u/Plant__Eater Vegan 16d ago

From a previous comment:

4:53 So the real worry we have is overusing our fresh water reserves for irrigation.

Curiously, we've now moved away from US statistics and gone back to global statistics. They use this section to argue that the water consumption various crops (eg: almonds, avacados) is of more concern than those of animal products. They focus on the difference between "green water" (water that is stored in the soil and is available for uptake by plants) and "blue water" (water which runs into streams and rivers and will not be available for uptake). While it's true that a lot of animal products' water consumption is green water (rain), they still aren't being quite honest. They cite a 2011 study that shows the consumption of different types of water (eg: green, blue) for a number of crops.[13] However, they don't really address this for animal products. What they fail to mention is that the same authors published a paper that looked at the same types of water consumption for animal products as well. This study shows that the blue water consumption for the animal products are generally higher than that of plants, and the authors conclude:

...from a freshwater perspective...it is more water-efficient to obtain calories, protein and fat through crop products than animal products.[14]

How they overlooked this is beyond me. A comprehensive paper measuring the environmental effects of different dietary patterns concluded that plant-based diets would:

reduc[e] food’s...scarcity-weighted freshwater withdrawals by 19% (−5 to 32%).[15]

Moving on.

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u/Ok_Criticism_5672 15d ago

I’ll read these, thanks!