Household and industrial wastes that have been accumulated during the last 40-50 years in the territories of organized and spontaneous landfills (garbage dumps) are causes of pollution of natural water bodies near places of their locations. As results of the actions of precipitation and those of solar irradiation, there takes place drainage water formation; such waters are polluted with harmful and toxic ingredients. The known indices of pollution of industrial and surface waters as well as the technique of determination of the class of danger of solid household wastes have been analyzed. The application of this technique to liquid wastes is suggested, since the change of aggregate state must not restrict its application; on the contrary, a new useful unexpected result can emerge with this. A rather simple dimensionless index of toxicity has been chosen on the basis of the following examples: composition of the drainage waters of a specific landfill, content of harmful ingredients in them, excess ratio of their maximum permissible concentration. Such an index takes into account the maximum permissible concentration of the harmful substance in the ground as well as the fraction of the harmful ingredients in the total mass of the liquid waste. Using the dimensionless index of toxicity, there are drawn bar charts from which the sequence of removal of harmful components from the liquid mixture can be determined; starting with the component with the least value of dimensionless index of toxicity which characterizes the most dangerous component.