Total dissolved solids (TDS) is the total amount of solids dissolved in the water, including soluble hydrogen carbonate ions, chloride salts, sulphates, calcium, magnesium, sodium, potassium, volatile solids and non-volatile solids. Its concentration will affect the taste of drinking water. A way to measure it is to filter the water sample (0.45μm), dry the solution at the temperature of 103℃ to 105℃ and then weigh the remaining residuals.