But if it worked that way (using a small amount of water over and over to clean) would be gross and unsanitary in this case. One could filter it but that costs a lot of energy and changing a filter weekly on your shower pod would not be very green.
But you don’t want to sanitise your skin, just get the dirt off, so I don’t see any real issues.
Have you ever taken a bath?
It seems like you can answer these questions for yourself rather than asking a stranger on the internet.
Let us know what you find.
I would have quoted that if it were easy to find, or quantify. It's not. I encourage you to do so, put the work in, and let us know what you find.
Its not that I don't agree with you, it's that I want you to do the work for yourself.