Whether you can drink water before a colonoscopy depends on the type of colonoscopy. Painless colonoscopy avoids drinking water; general colonoscopy can be done with a small amount of water, but under the guidance of a specialist. When doing general colonoscopy, since the patient is in a conscious state and needs to take medication, he or she should drink under the guidance of the doctor. When doing painless colonoscopy, which is performed under anesthesia without consciousness, you should not drink water 2 hours before the colonoscopy. Colonoscopy includes ordinary colonoscopy and painless colonoscopy, which can visually observe whether there is any abnormality in the intestines. Before the colonoscopy, you need to take laxatives in advance under the guidance of the doctor, and you need to take a large amount of water at the same time of taking laxatives to promote the discharge of feces and to empty the intestines. If you already drink water before the colonoscopy, it is recommended that the patient inform the doctor to avoid unnecessary harm.