It is common to hear things like it takes one gallon of water to create a single almond, or watering a lawn can take X gallons per month/year, or it takes X gallons to make one pound of beef or yield X pounds of alfalfa.
My question is, is that water “gone forever”? Or does the water thats used return to the water table/cycle in some other form. When you water the lawn does a large amount of that seep into the ground, evaporate, and return to the atmosphere?
Or is the water used in these ways truly gone forever (in terms of humans being able to use it again)?
It’s not gone forever. However, it may be in a less useful place.
For example, a well draws water from an aquifer, an underground reservoir; which is refilled by rainwater soaking into the ground. But if water is drawn out of the aquifer faster than it is replenished by the rain, eventually the well will run dry.
Even if that water is still on the planet, it’s not available to your well; and so your well has become useless.
Even worse: the nonsense of alfalfa in California. All the residential use accounts for only 15% in this state and most of it does not come from aquifers.
Now, Alfalfa is cultivated to be sold as cattle/horse feed to foreign countries and wastes a ton of water. Same for almonds and other “boutique” crops that don’t contribute in any way to the end of hunger and fill the pockets of few with money at the expense of public water.
You can’t destroy it and it doesn’t go anywhere. It just gets moved around and used for different things at different times.
Water lawn > Grass uses water to grow more grass > humans mow lawn > grass clippings dry out > water returns to atmosphere
What about something like electrolysis where it’s separated?
If you keep them separate sure, but the moment you burn hydrogen it just turns back into water.
That was kind of my arm chair guestimate of how it worked, that it wasnt truly lost for good but transferred around
If everyone on earth died at once and decomposed, how much water would be returned to the environment?
Very little, tiny fractions of a tiny fraction of a percent of the water on the planet.
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Sometimes it becomes toxic. Sometimes it’s relocated to a different watershed. The only time it is removed is when it’s split into O2 and H2, but the oxygen tends to stick around, and the hydrogen will soon reunite with oxygen
Another factor to add to these answers: if the water has been treated (if it’s mains water), then a not inconsiderable amount of electricity (and so carbon emissions) will have been used to treat it, and probably quite a lot more electricity will have been used to pump it around the country. So using water is also burning energy
Water is a bit more complicated than ordinary ressources, watershed are mostly local and it’s hard to transport water over large distances. To make-it simple, saving water in Scotland won’t bring more water to the Sahara.
All the water we use comes from rain (snow), and it would either go to the ground where it could be pumped, or join stream them rivers and flow downstream. A part of the water you use upstream will evaporate, and therefore won’t flow downstream, which is the cause of big geopolitical conflict, especially in dry regions. This water will still evaporate and at a point fall back on the ground as rain, but you don’t really control where (and when) the rain falls, moreover, with global warming, a hot atmosphere can store water than a cold one, leading to “less rain”.
Another issue is ground pollution. If you keep the ground clean, you can pump water, people have stuff to drink, farmer can water their crop and so on, but if there is any pollution you might have non drink water in the ground or even contaminate the plant you water with it, meaning that water is lost… forever
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