Some water purifiers in the Xiaomi/Mi Home APP display TDS, and some water purifiers display mg/L.
TDS is an acronym for Total dissolved solids, which indicates how many milligrams of dissolved solids are dissolved in 1 liter of water, in milligrams per liter (mg/L) or ppm (see Supplementary Notes). The higher the TDS value, the more impurities the water contains.
Total dissolved solids refers to the total amount of all solutes in water, including both inorganic and organic content. Generally, the conductivity value can be used to roughly understand the salt content in the solution. In general, the higher the conductivity and the higher the salt content, the higher the TDS.
In inorganic substances, in addition to the components dissolved in the form of ions, there may also be inorganic substances in the form of molecules.
Since the organic matter and molecular inorganic matter contained in natural water can generally be ignored, the salt content is also generally referred to as total dissolved solids.
Desalination rate: The water purifier produces water for a few minutes. After the TDS value is stable, (tap water TDS—pure water TDS)/tap water TDS, it is normal for the obtained desalination rate to be ≥85%.
In general, the lower the TDS value, the less dissolved solids in the water and the purer the water.
However, in certain water, TDS cannot effectively reflect the water quality, such as electrolyzed water. Due to the significant increase of charged ions such as OH- in the electrolyzed water, the corresponding conductivity increases abnormally. For example, the pure water with the original TDS at 17 is electrolyzed The TDS value of alkaline water obtained after water machine electrolysis is about 300.
After being filtered by the reverse osmosis water purifier, the TDS of the tap water will be greatly reduced. The TDS difference between tap water and pure water reflects the filtering effect of the water purifier.
Under normal circumstances, after the water purifier is not used for a long time, the TDS value of pure water will slightly increase due to osmosis, which is a normal phenomenon and can be reduced by continuous water production.
Tip:
1. The PPM value represents the solute concentration in the aqueous solution; ppm represents one part per million (example: 1ppm represents one part per million);
For solution: that is, 1/1000 ml of solute in 1 liter of aqueous solution, then its concentration (solute mass fraction) is 1 ppm.
2. The national standard GB5749-2006 "Sanitation Standard for Drinking Water" has limited requirements for total dissolved solids (TDS) in drinking tap water: total dissolved solids≤1000mg/L (conversion relationship: 1mg/L=1ppm).