Tap water flows down from the mountains, and sometimes it flows a long way to reach the reservoir. During this period, there will be a lot of bacteria and some pollutants. Although people will add some chemicals to make the water cleaner and let some impurities settle down, such as adding alum, there are still some bacteria that cannot be removed. Therefore, when drinking tap water, it is best to boil the tap water before continuing to drink it. Bacteria will die at high temperature, so that drinking boiled tap water will not be harmful to our health. Besides, boiled water can be better absorbed by our bodies. Drinking water is not as pure as it has become. In daily life, just like drinking pure water, the more you drink, the better. It will lack a lot of minerals. So tap water is good drinking water, but remember to boil it.