TDS is a concept introduced from abroad, which is the abbreviation of total dissolved solids in English. Refers to the concentration of total dissolved substances in water, and the unit is mg per liter (mgl), which mainly reflects the concentration of Ca2+ MG2+ Na+ K+ plasma in water. It has a good correspondence with the hardness and conductivity of water. The smaller the TDS value, the lower the plasma concentration of Ca2+ MG2+ Na+ K+ in water and the smaller the conductivity.
A small TDS value does not mean good water quality, and a high TDS value does not mean poor water quality. Qualified drinking water standards must meet microbial indicators (bacterial count), toxicological indicators (plasma concentration of heavy metals), sensory characteristics (color, smell and taste visible to the naked eye), general chemical indicators and radioactive indicators. Healthy and clean domestic water must not contain pathogenic microorganisms, and chemicals and radioactive substances in the water must not endanger human health and have good sensory characteristics. In many cases, in the process of testing the quality of water purifier, TDS value is often used to verify the purification effect of water purifier.