2. Tap water: Groundwater or surface water (water from rivers and lakes) is used as the water source, and after a series of treatments such as clarification and disinfection, its water quality meets the national drinking water standard, but it may cause secondary pollution if it flows into the water tanks of residents with poor sanitary conditions, so it cannot be directly drunk, and it must be boiled before drinking.
3. Natural mineral water: Natural spring water from deep underground or artificially mined groundwater, containing a certain amount of mineral salts or trace elements and carbon dioxide gas. The national standard has very strict regulations on this, and it is necessary to ensure the hygiene and safety index of water during mining and filling.
4. Pure water: refers to the water that meets the quality standard of drinking water, is treated by appropriate treatment methods such as ion exchange method and distillation method, and can be directly drunk without adding any additives. Its characteristic is not only to reduce the concentration of inorganic salts, but also to remove suspended solids, such as bacteria and viruses, in the process of treatment, so that water can be purified.
5. Boiling water: boiling water can precipitate some minerals, reduce the hardness of water, evaporate low-boiling organic matter and kill bacteria. It is the most commonly used and accustomed drinking water for China residents.