I live on an island dealing with water shortage issues in our sole source aquifer. The community has enacted a number of irrigation restricting laws, and there is significant discussion about various other water-saving practices such as turning off the water when you do the dishes, shorter showers, etc.
To clarify, the sole source aquifer under our island is like a lense of fresh water surrounded by salt water. If too much water is pumped out without recharge from rain, the saline water moves inland and can affect wells. So there is an obvious need for water conservation. But is water from an extended shower or letting the tap run for a long time "lost" as it would be in a municipal system drawing from a reservoir? My thinking is that such water is returned directly to the source, and would therefore not be lost.
I understand that irrigation is a completely different situation. I also understand that in some areas huge amounts of pumping could supercede the ability of water from the septic system to return to the aquifer AND that it might exceed the ability of the system to contain the water.
But in general, drawing water from the aquifer for use in a shower, and then returning it underground would have a negligible effect on the net amount of water in the aquifer. Is this thinking flawed.