For a colonoscopy in the morning, you can drink one dose of oral sodium phosphate salt solution at 8:00 pm the night before, and another dose 3 hours before the exam, which needs to be consumed within half an hour. Sodium phosphate salts need to be taken before the colonoscopy to cleanse the bowel and prepare it for the test. To take the oral solution of sodium phosphate salt, take 45 ml of the oral solution of sodium phosphate salt at 7:00 p.m. the day before and mix it with more than 750 ml of warm boiled water and then take it. It is also okay to drink it at 8 pm the day before. At least 3 hours before the examination, take a second dose of sodium phosphate oral solution in the same way, drinking plenty of water and moving around until the stool is colorless, clear and watery. Sodium phosphate oral solution should be used under the supervision of a medical professional, and it is recommended that you follow your doctor’s instructions on how to take it.