Colonoscopy preparation begins several days before the procedure, when you start a liquid diet to empty your colon. This eMedTV article further explains the colonoscopy preparation process, including what to expect and what you can and cannot eat.
The process of cleaning out your bowels before a colonoscopy is called a bowel prep. This eMedTV segment describes the steps involved in this procedure, including which medicines are often used and what to expect after taking the drugs.
There are a few ways to do a bowel prep; using Fleets Phospho-Soda is a popular method. As this eMedTV article explains, using Fleets Phospho-Soda (a laxative) involves taking the drug in 2 separate doses, accompanied by lots of water.