If you drink boiled tap water, it is not harmful to your body. However, if you drink untreated tap water directly, it may be harmful to your body. Although tap water is processed and disinfected, there are still many chemicals and disease-causing microorganisms in the tap water delivery process, which may lead to gastroenteritis and other diseases, abdominal pain, diarrhea, and long-term health hazards if consumed directly. If you drink boiled tap water, also known as plain water, is not harmful to the body. Because the process of high-temperature cooking will make the tap water in the vast majority of pathogenic microorganisms are killed, this time the safety of tap water has been greatly improved. In short, drinking tap water is harmful to the body can not be generalized, it is recommended not to drink directly from the tap, boil and then drink.