PhilosophicalCat
This is anecdotal - I'm not sure if it helps:
I've noticed when I do the SWF, all liquids leave via the colon. I usually follow up with 2 - 4 glasses of plain water. At first, liquids leave via the colon, but most of it leaves via the bladder.
I think that doing this helps to wash out extra salt from the body, placing less strain on the kidneys to balance the salt/water levels in the body.