Colon cleansing during a Water Fast.

I'd like to know the best way to clean the Colon during a long Water Fast.
I'm not into enemas or colonics. In the past I've tried the saltwater flush of The Master Cleanser , and have even used Oxypowder . Then, of course, one can do nothing (like the Natural Hygienists), and let the body clean itself. I'm thinking my body needs a little help.
What are the thoughts here?