The purpose of the work was to analyze the possibilities of using the leachate pollution index (LPI) to assess the state of contamination of leachate waters, using the results of monitoring and extended scope of research. Based on the conducted analysis, it can be noticed that the use of the results of determinations in the current scope for the assessment of the effluent waters is ineffective and may provide incomplete information on the actual impact of the landfill on the aquatic environment. The valid range of the physicochemical properties of leachate waters should be verified, because it relies heavily on the study of heavy metal content, but does not take into account other parameters, which are characterized by high variability. It has been shown that the addition of only 3 parameters determined within the scope of the monitoring scope in force may change the significantly calculated LPI value, and thus provide additional information on the contamination of leachate waters at a given facility.