With the improvement of economic level, most people have started to use pure water instead of tap water, that is because tap water contains a large number of harmful substances, such as trihalomethanes, trichloromethane, dichlorobromomethane, trichlorobromomethane and tribromomethane, etc.. So drink the water must be boiled, otherwise it is equivalent to chronic suicide. Here are a few kinds of water can not drink, take a look at it. What kind of water can not drink? 1, do not open the water bladder cancer, rectal cancer experts point out that drinking unboiled water, the possibility of bladder cancer, rectal cancer increased by 21% -38%. When the water temperature reaches 100 degrees Celsius, these two harmful substances will be greatly reduced with the evaporation of steam, such as continued boiling for 3 minutes, it is safe to drink. 2, thousand rolls of water diarrhea, bloating, coma and convulsions thousand rolls of water is boiling on the stove overnight or a very long time, there are electric water heaters repeatedly boiling water. This water is boiled for too long, the water does not volatile substances, such as calcium, magnesium and other heavy metal components and nitrite content is very high. Drinking this water, will interfere with human gastrointestinal function, temporary diarrhea, bloating; toxic nitrite will also cause hypoxia, serious people will coma convulsions, and even death. 3, steamer water premature aging, cancer steamer water is steamed buns and other leftover pot water, repeatedly used steamer water nitrite concentration is very high. Drinking this water often, or using this water to boil rice, will cause nitrite poisoning; gutter often with the water into the body, but also cause digestive, mental, urinary and hematopoietic system lesions, and even cause premature aging, cancer. 4, aging water esophageal cancer, gastric cancer commonly known as “stagnant water”, that is, water stored for a long time, often drinking this water, the minors will significantly slow down cell metabolism, affecting physical development; middle-aged and elderly people will accelerate aging; many places, the increasing incidence of esophageal cancer, gastric cancer, may be related to long-term drinking aging water. Toxic substances in aging water also increase with the increase in water storage time.