– If water is constantly recycled, why are we concerned about conservation?
In: Planetary Science
The amount of water stays (roughly) constant, but the amount of clean, drinkable water in places where we need it is not.
That’s pretty much the long and short of it.
A given amount of water falls as rain in a particular place. If you use more than is available, then you run out.
It’s like why do you worry about running out of money if your job pays you every two weeks?
Lots of areas have a rainy season and a dry season. You need to collect water in the rainy season and then not use it all in the dry season.
We are not running out of water on this planet. We are running out of usable water.
For example, The amount of water in the oceans is near limitless…. But we can’t use it for drinking or irrigation unless we take the salt out of it, which is expensive to do ( and then it would have to be transported inland ) .
Ultimately, it’s a question of energy.
Cleaning water takes energy. Moving water from place to place takes energy.
If we wastefully use clean water from local aquifers, that means we have to spend more energy to clean more water, or to move water from other locations to our location.
If water (in the form of snow) simply deposits itself on a local mountain, and then later melts and flows down to your city, it’s relatively cheap to get it into a form that you can use in your home or business. But if you use more water than that meltwater can provide, you might need to have water trucked in from elsewhere, or build a pipeline to bring it in from elsewhere. Both options use massively more energy than just letting snow melt and flow down to you on its own.
Not every clean water source we use replenishes at the rate we use it. For example, much of the US depends not on the water cycle, but on aquifers, that are limited in amount and refill *very slowly.* And, using more water from aquifers doesn’t mean the clean water in the world will increase by that amount after it is used. There’s *lots* of water in the global system, and that additional amount we are adding makes little difference–after all, the vast majority of water is in the ocean (~96%), and a vast majority of fresh water is ice (~70% of that remaining ~4%).
Using more water than our fresh water sources can replenish genuinely means less for the future, or much more quickly needing to find other sources, which our system isn’t equipped to accommodate now or in the near future–nor are we investing in it enough for it to be viable soon to meet our demands.
Many parts of the world don’t have a whole lot of water. Where I live, water is abundant, I am less than a mile from a large river and about 2 miles from an absolutely massive lake. It’s easy to drill a well here if you don’t live in town. For many parts of the world it’s the opposite, there’s little to no water on the surface and you have to drill extremely deep to find water underground.
California is a good example of the consequences of using too much water. Lake mead is the primary source of water for California and neighboring southwestern states, this lake is at about 20% capacity versus what it was 100 years ago. It did rise a little bit last year but it’s on track to go dry in the near future. This is largely because the river that feeds it is likewise going dry caused by overuse of water and warmer winters leading to less snow pack in the mountains so there’s less snow to melt in the spring and feed the lake.
CA also taps into natural underground aquifers and has pumped so much water out that a lot of them have collapsed. When they collapse, they cannot refill to their old capacity and it’s not some thing you can fix, they are several hundred feet down. This can cause the land to sink up to 20 feet.
A lot of wasted water results from farming in place is not suitable for farming like the American Southwest. Not only that farmers are growing crops that require a lot of water like almonds or alfalfa. Growing crops in hot desert like environments means, you have to water crops even more because the harder it is the more water evaporates, it’s one massive feedback loop.
So yes water is not destroyed when we use it. But the water cycle doesn’t necessarily deposit that used water right back where it was.
Some answers have said that, what is limited is the supply of clean drinkable water. Another issue in water conservation is aquifers. Some areas rely on underground water sources that are being depleted faster than natural processes can refill them. The Ogallala, which provides much of the water for the Great Plains, is commonly cited example.
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