Drinking only water for a day can’t cleanse the intestines, and it will lead to insufficient energy intake and damage the function of the gastrointestinal tract. Cleansing is mainly to remove the feces in the intestinal tract, simply drink water without eating can promote urination, but often can not well promote the discharge of feces, do not eat feces volume is insufficient, there may be constipation, can not be cleansing. And if you only drink water a day, the body will take in insufficient energy, but also on the gastrointestinal tract function leads to some damage, slow intestinal peristalsis and so on. If bowel cleansing is needed because of intestinal examination or intestinal surgery, it is often necessary to take pro-excretory drugs, such as lactulose and compounded polyethylene glycol electrolyte dispersions under the guidance of a doctor, and you cannot drink only water.