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)?
Depends. Sometimes the water gets dirty and needs to be treated, sometimes it evaporates and needs to rain, sometimes it could be reused as is
In very rare cases (nuclear fusion) the water is destroyed into its primitive elements
Simple electrolysis will split water molecules into hydrogen and oxygen.
Nuclear reactions will change the atoms, but you don’t have to go that far to break down water.
You don’t even need to go that far. Water used in concrete is locked in as a structural component. That’s why concrete is described as ‘setting’ instead of just ‘drying’.
It’s pretty easy to break water down, but it’s also super easy to make it - just burn anything organic.
Usually you can’t see the water being formed, but there’s actually a really common example: car exhausts on a cold day. If you notice a bit of water dripping out of the tailpipe of the car in front of you at a red light, that’s actually the moisture in the exhaust fumes condensing on the cold tailpipe.