Physical and chemical characteristics and dynamic characteristics of natural water that has not been polluted by human activities. Physical characteristics mainly refer to the temperature, color, transparency, smell and taste of water. The chemical properties of water are determined by the gas, ions, molecules, colloidal substances and suspended substances, microorganisms and the content of these substances dissolved and dispersed in natural water. The dissolved gases in natural water are mainly oxygen and carbon dioxide; the dissolved ions are mainly potassium, sodium, calcium, magnesium, chlorine, sulfate, bicarbonate and carbonate ions. Bioprotoplasms include nitrate, nitrite, dihydrogen phosphate and hydrogen phosphate ions. In addition, there are certain trace elements such as bromine, iodine and manganese. The colloidal substances include inorganic colloidal silica and humic acid colloids. Suspended solids are mainly inorganic. Microorganisms include bacteria and coliform bacteria.
Drinking water class I: National nature reserve, water quality is not polluted.
Drinking water class II: cleaner, can be used as drinking water after filtration.
Drinking water class III: filtered and cleaned as general industrial water
Category IV: General agricultural water, irrigation.
Category V: General landscape water.
Poor V category: Useless dirty water.