Total dissolved solids, abbreviated as TDS, is a measure of the combined concentration of all dissolved substances in water. Within the reverse osmosis industry TDS is known as as the total cations and anions in the water. TDS is the sum of either anions or cations in the water. TDS is usually expressed in parts per million (ppm) or milligrams per liter (mg/L) of water. These substances can include inorganic salts, minerals, metals, cations (positively charged ions), anions (negatively charged ions), and some organic matter.
The measurement of TDS provides an indication of the overall quality of water and is commonly used in water quality assessments for various purposes, including:
TDS can be measured using various methods, including conductivity meters, which estimate TDS based on the electrical conductivity of water. While TDS is a useful indicator of water quality, it doesn't provide information about the specific types of dissolved substances. For a more detailed analysis, additional tests may be required to identify and quantify individual ions and compounds present in the water.