There are many different schools of thoughts on how you should keep your colon clean.  One of the more mainstream methods of doing this is through the use of Colon Hydrotherapy.  This is also a process that is known as colonics and it can help you to keep your colon clean by the use of low pressure water.  The person administering the colonic will gently force this water into your colon to help wash away any debris is that may be stuck and impacted in the walls.  You will probably be surprised at the amount and type of debris that comes out of your body when this procedure takes place.