First, we see the full description of abbreviation. T means total, D means Dissolved and S means Solids. Total Dissolved Solids. Why it is important for us ? World Health Organization (WHO) Guidelines for Drinking Water Quality The palatability of water with a total dissolved solids (TDS) level of less than about 600 mg/l is generally considered to be good; drinking-water becomes significantly and increasingly unpalatable at TDS levels greater than about 1000 mg/l. The presence of high levels of TDS may also be objectionable to consumers, owing to excessive scaling in water pipes, heaters, boilers and household appliances