[google is very unhelpful, it’s broken now. I can’t find any posts explaining the specific thing I want to know]
Was asked this question by a friend.
When we say that producing one item of clothing uses x amount of water. She doesn’t see the harm because the water used to grow cotton doesn’t disappear “it’s part of the cycle”.
Pollution must be a factor right? There is a difference between drinking water, saltwater and contaminated water? (Surely they’re not using clean drinking water for production?)
Exasperated by the fact that production is usually performed in areas with poor regulation/infrastructure.
(Is it inherently damaging, or damaging because of how it’s performed?)
Is the water “used” because it becomes vapor? Is it used because the molecules are taken apart? Either way shouldn’t this technically be reversible?
[I am not very articulate, and I find it very difficult to organize my thoughts to words. This question ended up frustratingly inprecise!]
Edit: thanks for the good responses:)
In: Biology
Are you asking why it’s called ‘water use’?
Are you asking what kind of water is used to produce clothing?
Or are you asking why high water usage is an issue in the clothing industry?
Only about 2.5% of the water on earth is fresh water. Of that, the vast majority is locked up in groundwater, the polar icecaps, and glaciers. The water in the ground mostly stays there for hundreds to thousands of years, and is not particularly accessible to us. So it turns out only a very small amount of fresh water is actually available to us in the form of rivers or aquifers.
What happens when you use vast amounts of water to, for example, irrigate cotton, is that that water ends up a) in the ground, and b) in the oceans. Both are pretty inaccessible. IN ADDITION, the process of doing that washes vast amounts of fertiliser and pesticides/herbicides into both the groundwater and into the oceans. Neither of which is a good thing.
You might reasonably ask why we don’t just desalinate sea water, and the answer to that is that we DO, but it’s an incredibly power intensive, and thus expensive, process. So it tends to be the fresh water resource of last resort, not first resort.
I agree with your friend. Water is returned to the hydraulic cycle. One could argue that water is diverted to grow the cotton, but this is true with most industries that use water. Cotton itself is 100% biodegradable as well.
If you pump up water from an aquifer that took tens, hundreds, or thousands of years to fill up, then the water is essentially used.
Water moves very slowly through soil.
Just Google California aquifer depletion
Let’s say you have a gallon of water. Maybe it was easy to get, maybe it was hard to get, maybe it was expensive, but it’s yours.
You drink half of it. You can understand why that’s not useful anymore. You can understand why that half gallon is gone. It’s pee now.
Sure, we could filter it or let it evaporate and turn into rain, but it’s not in the “drinkable water” part of the water cycle.
Now let’s dump the second half into the ocean. It’s still part of the water cycle. It’s not *gone*.
It just doesn’t do you any good.
And if you need more, you need to do whatever you did to get that first gallon. Maybe that means finding it usable in nature, transporting it elsewhere or maybe that means filtering or desalination.
There’s a lot of water on earth. Not a lot of it is fresh, easy-to-get and clean. That’s why it’s a problem if humans collectively use more than can be easily replenished, and why there is concern about which uses of water are reasonable or wasteful.
Think of it as using the easily accessible water. Over a certain amount, it will require significant effort/energy/investment to use or clean which would greatly increase the cost people would have to pay the utility.
So all discussion about water usage is really a discussion about how to effectively use what we have at the price people are currently paying.
There is a cycle but it has to be in balance.
Water goes up into the air, falls on mountains and becomes rivers.
If we take too much water from the river, no more rain falls, so the river dries up.
For evidence: look up the Murray River is Adelaide, Australia. It routinely doesn’t reach the sea any more as it gets intensively used for farming further upstream.
Water is naturally cleaned by evaporation -> rain. Then it gathers in rivers and lakes. This water is relatively cheap to clean enough for household use or drinking water. But there’s a limited amount in each part of the world per year.
Using it for watering, either before or after cleaning, makes it no longer available. Much evaporates, some runs off but becomes more dirty than before.
Cleaning up the used water, or cleaning salt water, or transporting long distance is *much* more expensive. So it’s not something people living there want/can afford. So it’s effectively less water for them.
You’re correct that using water for farming doesn’t decrease the total amount of water on earth. But it does decrease the amount of water available in the region, the vapor would be blown elsewhere or water in the ground would leech elsewhere. Usually when talking about water usage for farming or factories it’s about the regional ecological impact
It takes time to replenish.
The water cycle may give say 30 million tonnes of water to a given country per year.
You can use it up faster and run low on water if you produce too many water intensive products.
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