Drinking a moderate amount of water prior to an abdominal CT examination usually does not affect the image quality of the CT scan, but proper gastrointestinal preparation and appropriate fasting is required upon request. In abdominal CT examination, drinking water also has its certain role, briefly described as follows: 1. Water can be used as a contrast agent, which can make the gastrointestinal tract fully filled and change the density difference with the surrounding tissues, and it can also be beneficial to the detection of lesions in the gastric cavity. 2. If it is an abdominal enhancement examination, drinking water also has a hydration effect, which can quickly facilitate the excretion of contrast medium from the kidneys. 3. When checking the small intestine, you can drink mannitol and water, which can show the small intestine more clearly and make up for the lack of good means of clinical examination of the small intestine. Patients should fast 4 to 8 hours before the abdominal CT examination, except in the case of emergency medical treatment. One week before the abdominal CT examination, patients should not do gastrointestinal barium contrast and should not take drugs containing metals. The purpose of gastrointestinal preparation is to minimize the interference caused by the high-density substances left in the intestine as well as gases to the CT images, so as to improve the radiologist’s correct diagnosis of the images. Therefore, it is recommended that appropriate fasting be done before the abdominal CT examination, and a moderate amount of water can be consumed.