1. Overview
Total dissolved solids (TDS) refer to the total amount of inorganic salts and organic substances that are dissolved in water. The main components of TDS include a variety of ions such as calcium, magnesium, sodium, potassium ions; anions like carbonate ions, bicarbonate ions, chloride ions; as well as sulfate ions and nitrate ions.
The amount of total dissolved solids is directly related to the taste of drinking water. The following lists the relationship between different TDS concentrations and the taste of drinking water. Excellent: less than 300mg/L; Good: 300-600mg/L; General: 600-900mg/L; Poor: 900-1200mg/L; Undrinkable: greater than 1200mg/L. Similarly, the concentration of TDS in drinking water is too low, and it will be too bland and unpopular.
TDS in water comes from natural sources, sewers, municipal and agricultural wastewater, and industrial wastewater. Salt spread on the road to prevent icing can also increase the amount of TDS in the water. The natural source of TDS is greatly affected by the salt content of ores in different regions. Available from 300mg/L up to 6000mg/L.
Although there are numerous studies on the relationship between drinking water hardness and health, there are currently no reported associations between TDS in drinking water and population health. In earlier studies, TDS in drinking water has been reported to be inversely associated with cancer, coronary artery disease, arteriosclerosis and cardiovascular disease. It has also been reported that TDS in drinking water is inversely associated with mortality.
2. Determination of limit values in drinking water
Components in TDS, such as chlorides, sulfates, magnesium, calcium and carbonate, have been identified as corroding or scaling water pipes. High mass concentrations of TDS (>500mg/L) can reduce the service life of water pipes, water heaters, hot kettles and other household appliances such as kettles and steam irons.
Although the situation is not exactly the same, in general, the TDS content in drinking water is less than 1000mg/L is more acceptable. The high concentration of TDS will cause unpleasant taste and shorten the service life of water pipes, water heaters, kettles and other household appliances, thus causing resentment among residents. Similarly, the concentration of TDS in drinking water is too low, it will be too bland and unpopular, and it will also cause corrosion to the water pipeline. Therefore, the limit standard of total dissolved solids in China's "Sanitary Code for Drinking Water" is 1000mg/L.
Zhang Yuchun, a professor of environmental science and engineering at Tsinghua University, pointed out that drinking well water or tap water with a certain soluble solid content and a slightly alkaline PH value is good for human health.
Dissolved solids content refers to the amount of minerals contained in drinking water. The more minerals in drinking water, the harder the water will be.
According to Professor Zhang Yuchun, well water and tap water with a certain soluble solid content are first easy to be absorbed by the human body and can supplement some trace elements needed by the human body. At the same time, well water or tap water with a certain dissolved solid content can also effectively block the absorption of toxic and harmful substances by the human body, thereby reducing the damage of these toxic and harmful substances to human health.
