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.
The question is a bit like “If I spend all my money, is it truely gone forever or did it just return to the global financial streams?”
Like with the money, water exists in very different states of usefulness. Sea water, for example, is incredibly abundant, but using it requires desalination, which requires enormous amounts of energy.
Ground water is really useful, because it’s where you need it and it’s usually pretty clean.
Rain clouds mostly pull their water from the sea. Hence using water e.g. in agriculture will not increase the amount of rain by any significant amount.
Ground water replenishment thus doesn’t depend on the amount of ground water spent for e.g. lawns. Similar as your wages usually don’t depend on how much money you spend on a holliday.
So if you waste ground water, it’s mostly just gone, while you wait for rain to refill it. Sadly, in most regions that happens far slower than people are spending their precious water resources on useless nonsense like a green lawn.
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
If you keep them separate sure, but the moment you burn hydrogen it just turns back into water.
So then the truth of the matter is that we can create water from hydrogen and oxygen and we can also destroy water by reducing it to its elemental compounds. As such, water can be created and can be destroyed, meaning that the overall level of water available on earth can change over time, however our commonest uses for water have it not be destroyed and eventually return to the water cycle.
That was kind of my arm chair guestimate of how it worked, that it wasnt truly lost for good but transferred around
The bigger issue is that while the water still exists, it may no longer exist in a useful location. It could be pulled from a reservoir in a drought stricken area, evaporate and drift to some other area where it causes a flood.
That’s an extreme example, but I hope it makes the point that the location of water is just as important as its existence.
If everyone on earth died at once and decomposed, how much water would be returned to the environment?
It’s a cycle, but it’s not in balance.
There is a lot of water on earth. Most of it is salt water which is not usable for crops or consumption etc.
The graphics on this Wikipedia will give you an idea of the distribution: https://en.m.wikipedia.org/wiki/Water_distribution_on_Earth
The water we use for food production, watering lawns, bathing and toilet flushes is pumped from the fresh ground water, which is only about 0.76% of all water on earth.
When we use water, it will eventually, one way or the other, flow into the sea, where it turns into salt water. The evaporation from the sea will create clouds that will rain and seep down to become fresh ground water again.
The problem is that we are basically taking the tiniest bit and turning it into the largest faster than it can be replenished.
