Can I drink water that has been boiled twice?

We all know that boiled water has very good effects. Drinking boiled water regularly can excrete toxins from the body through urine. When you have a cold, drinking boiled water can make the body sweat and make the cold heal quickly. However, it is best to boil the water before drinking it, because the bacteria in such water are generally killed. But sometimes, the water is boiled twice. Can it still be drunk in this case?

1: One situation is that the water is boiled, then heated again after it cools down, and then boiled again. There will be no safety issues if it is boiled once or twice.

2: But sometimes you use an automatic heating kettle (water dispenser), which will automatically reheat as long as the temperature drops to a certain level. If the water in the water heater is heated repeatedly for more than ten hours or several days (some people call it "thousand-boiled water") without being replaced, the water may contain higher levels of health hazards, such as harmful substances dissolved from the heating elements and containers, and some trace harmful substances contained in the raw water will also accumulate and increase. Generally speaking, this kind of water contains higher levels of nitrite.