The common reasons for feeling thirsty despite drinking a lot of water every day are viral cold, fire and diabetes. Drinking a lot of water every day but still feel thirsty, may be caused by viral colds, viral colds, fire will cause the human oral mucosa loss of water increased, the human oral mucosa loss of water increased, will cause the human body appears thirsty, dry mouth. It may also be caused by diabetes, a common symptom of diabetes is three more and one less, that is, more drinking, more food, more urine, weight loss, because of diabetes patients more drinking, more urine, easily lead to water metabolism in the body too fast, often cause drink a lot of water but feel thirsty. Drinking a lot of water every day or thirst caused by the cause is mostly bad, need to make targeted treatment for its exact cause.