Drinking a lot of water every day and still feeling dry mouth may be related to environmental factors, diabetes mellitus and uremia. 1. environmental factors: due to the hot weather, the environment in which the person is also relatively hot, people will sweat a lot, although every day to drink a lot of water, but with the perspiration continues to increase, will also feel dry mouth. 2. diabetes: diabetic patients with unstable blood levels can lead to increased osmotic pressure in the body, increased urination. 2. Diabetes: diabetic patients with unstable blood sugar levels, elevated blood sugar can lead to increased osmotic pressure in the body, increased urination, and then easy to feel dry mouth, need to drink a lot of water to relieve the symptoms of dry mouth. If the diabetic patient’s blood sugar level is not well controlled, it is easy to lead to drink a lot of water every day, but still feel the phenomenon of dry mouth. 3. Uremia: Uremia is mainly caused by insufficient secretion of antidiuretic hormone in the body or damage to the kidneys resulting in decreased sensitivity of the kidneys to antidiuretic hormone, which is manifested by increased urination, dry mouth, and drinking a lot of water. After excluding the influence of physiological factors, it is recommended to go to the hospital for the appropriate examination to clarify the cause of the disease, under the guidance of the doctor according to the specific conditions of symptomatic treatment.