After replenishing water, you still feel thirsty all the time, which may be caused by the following diseases: 1, diabetes, many diabetic patients have the initial symptom of dry mouth and urination, and often have the feeling of drinking a lot of water is not enough. 2, oral disease, a lot of oral disease will affect the secretion of saliva, resulting in dry mouth, such as mumps, submandibular inflammation, etc. 3, kidney disease, the kidneys are the human body is extremely important organs. If the kidney function is abnormal, the body's water loss and metabolism will be accelerated, and it will produce a feeling of frequent thirst. 4, the upper respiratory tract infection, patients with upper respiratory tract infection will not only be thirsty, but also feel the mouth and nose part of the dry abnormality.