The SWF (Salt-Water-Flush) is easier on the kidneys than the ES, becasue the SWF (Salt-Water-Flush) stays in the intestines and doesn't get absorbed, so the kidneys don't come into play at all.
Ah, good point, Let's see... As long as you only do the SWF (Salt-Water-Flush) about 3x a week tops, your colon will be getting exercise from the fiber, and it still gets massaged and exercised a tad by the SWF itself as it goes through.