Long-term use of tea instead of water may cause insomnia, dental fluorosis or fluorosis, anemia, gastrointestinal damage and other problems. 1. Insomnia: Tea contains a large amount of caffeine, which can refresh the mind, help the drinker to concentrate and excite the central nervous system. Tea instead of water at night can make people’s spirits uplifted, the nervous system is over-excited, leading to insomnia. 2. Dental fluorosis or fluorosis: tea contains fluorine, moderate consumption of tea can prevent dental caries, long-term tea instead of water, especially a large number of strong tea, may cause the accumulation of fluorine, resulting in dental fluorosis or fluorosis. 3. Anemia: tea contains ellagic acid, long-term tea instead of water may prevent the absorption of iron, causing or aggravating iron deficiency anemia. 4. Gastrointestinal damage: the caffeine in tea can irritate the mucous membrane of the gastrointestinal tract, and long-term consumption of tea can cause gastric mucous membrane damage, resulting in mucosal erosion, gastric and duodenal ulcers and other diseases. Moderate consumption of tea can play a positive role in hydration, summer and other positive effects, excessive consumption will cause harm to the human body, please do not long-term tea instead of water.