1, strain aging: yeast and lactobacilli and other strains of bacteria in the black tea bacteria will be aging due to a long time without water, resulting in a substantial decline in taste and nutritional value, losing drinking value.

2, breeding pathogenic bacteria: a long time without changing the water may lead to black tea bacteria breeding other pathogenic bacteria, such as mold, etc., which will make the black tea bacteria deterioration, drinking may trigger gastrointestinal symptoms, such as nausea, vomiting, abdominal pain, diarrhea, etc., and in severe cases may even lead to food poisoning, acute gastroenteritis.

3, appearance changes: black tea bacteria may be black, yellow, or have an abnormal sour taste, smell and other phenomena, these are the performance of black tea bacteria spoilage.

4. Therefore, it is recommended to change the moisture of black tea mushroom regularly, and pay attention to sealing and placing it in a cool, ventilated and dry place to maintain its quality and safety. When drinking, it should be poured and diluted with water to avoid irritation to the gastrointestinal tract and causing uncomfortable symptoms. If the black tea bacteria brewed for two years without timely water change, it is best not to drink again, because there may be other harmful substances or stray bacteria, causing adverse health effects.