If you are using Fleets Phospho-Soda for your colonoscopy bowel prep, on the day before your colonoscopy, you should only have clear liquids to drink or eat the entire day. This includes: black coffee or tea, bouillon, water, juice (specifically apple, grape, or cranberry), soda pop, Gatorade^{®, hard candy such as Life Savers or lemon drops, and Jell-O.}

Make sure not to eat or drink anything with blue or red dye. Red dye, like the kind in cherry flavored Jell-O, looks like blood inside your intestines. Blue dye makes it more difficult to see the inside lining of the colon. You should also avoid any dairy products like milk, ice cream, or cream soup.

At 4 pm, you should begin by taking 1 ½ tablespoons of the medicine with a half cup of water or root beer. You will take the same amount again at 7 pm.

In between 4 pm and 7 pm, you will need to drink at least three to six 8-ounce glasses of clear liquid. Try to drink more if possible.

The Fleets Phospho-soda works by taking extra water from your body and moving it to the colon. This causes the feces in your colon to break up and start diarrhea. It can take up to 4 hours for the diarrhea to start. In order to keep you from becoming dehydrated, it is very important that you drink as much liquid as possible throughout the day.

After you have taken both doses of the Fleets Phospho-soda, you can still have clear liquids until 4 hours before your colonoscopy.  Medical Supply.