My city is in the middle of the worst drought in recorded history. My showers are typically under 2 minutes and I have to shower with a bucket to catch otherwise wasted water to use to flush the toilet. I also shut the water down when I am wet enough so I can scrub myself without having unneeded water flowing then start it back up to rinse.
Plus, water is damn expensive!
Who here really has the time to stand, think and waste in the shower?
The cost is that you deplete the aquifer. Generally speaking, water pumped out of the ground doesn’t replenish (except on geologic time scales). That’s what I meant by the fossil fuel comparison. It’s not like taking water from a stream or a lake replenished by snowmelt. Once that aquifer is dry, it’s dry, and the land becomes dead.
Hopefully some of my pee from the septic tank makes it over to my well then.