How is total dissolved solids (TDS) measured?

Total dissolved solids (TDS) is measured by evaporating a known volume of water and weighing the remaining residue. This method involves taking a sample of the water, evaporating it completely, and measuring the weight of the residue left behind. The residue is comprised of all the inorganic and organic substances dissolved in the water, and this provides a direct measure of TDS.

In this process, the total weight of the solids remaining after evaporation reflects the concentration of dissolved substances in the original water sample. This method is considered a standard procedure for determining TDS because it gives a clear and accurate snapshot of the solids present in a specific volume of water.

Other methods, such as using a refractometer or measuring electrical conductivity, may provide indirect estimates of TDS but do not yield a direct measure based on residue. Similarly, filtering the water and weighing the filtered material identifies suspended solids rather than dissolved solids. Thus, the given method of evaporation and residue measurement is the definitive approach for assessing total dissolved solids.